The  Composition  of  the  Atmosphere 


With  Special  Reference  to  Its  Oxygen  Content 


BY 
FRANCIS  G.  BENEDICT 

Director  of  the  Nutrition  Laboratory  of  the  Carnegie  Institution  of  Washington 


WASHINGTON,  D.  C 

PUBUSHED  BY  THE  CARNEGIE  INSTTTUTION  OF  WASHINGTON 

1912 


•igitized  by  the  Internet  Archive 
I  in  2007  with  funding  from 
,    Microsoft  Corporation 


http://www:archive.org/detaiis/cbmf5osifi6 


FRONTISPIECE 


Apparatus  for  Analysis  of  Atmospheric  Air,  devised  by  Dr.  Klas  Sonden. 


Composition^  n 


With  Special  Refe' 


u)ntent 


PI  aUSHED  BY  IHC  C. 


M, 


It 


^;.;;*' 


^'- 


The  Composition  of  the  Atmosphere 

With  Special  Reference  to  Its  Oxygen  Content 


BY 
FRANCIS  G.  BENEDICT 

Director  of  the  Nutrition  Laboratory  of  the  Carnegie  Institution  of  Washington 


WASHINGTON,  D.  C 
PUBUSHED  BY  THE  CARNEGIE  INSTITUTION  OF  WASHINGTON 

1912 


CARNEGIE  INSTITUTION  OF  WASHINGTON 
PUBUCATION  NO.  166 


ISAAC  H.  BLANCHARD  COMPANY 
NEW  YORK 


CONTENTS. 


Part  I. 

Page 

An  historical  account  of  the  development  of  methods  for  determining  oxygen.  3 

Early  investigations  on  the  composition  of  the  air 4 

The  nitric-oxide  eudiometer    7 

The  beginnings  of  accurate  air-analysis    16 

The  foundations  of  modem  air-analysis 29 

Summary  of  historical  digest    66 

Part  II. 

Analyses  of  atmospheric  air  made  at  the  Nutrition  Laboratory 69 

Fundamental  essentials  of  accurate  air-analyses 71 

Apparatus  and  technique  used  in  this  research 75 

Detailed  description  of  the  apparatus  76 

Reagents  used   79 

Plan  and  methods  of  research 82 

Method  of  collecting  outdoor  air 82 

Method  of  using  the  apparatus  and  results  obtained 83 

First  routine  and  results  obtained   83 

Second  routine  and  results  obtained    88 

Control  analjrses   93 

Third  routine  and  results  obtained    94 

Effect  on  oxygen  absorption  of  high  and  low  temperatures 96 

Fourth  routine  and  results  obtained    98 

Fifth  routine  and  results  obtained   100 

Conclusions  from  results  with  fifth  routine    105 

Analyses  of  air  collected  on  the  Atlantic  Ocean    106 

Analyses  of  air  from  Pike's  Peak 108 

Analyses  of  street  air   109 

Analyses  of  subway  air 110 

Absorption  of  oxygen  by  potassium  pyrogallate   Ill 

Conclusions    114 

Sii 


99/^ 


THE  COMPOSITION  OF  THE  ATMOSPHERE 

WITH  SPECIAL  REFERENCE  TO  ITS 

OXYGEN  CONTENT 


PART   I. 

AN  HISTORICAL  ACCOUNT  OF  THE  DEVELOPMENT  OF 
METHODS  FOR  DETERMINING  OXYGEN. 


The  interest  in  meteorology  and  aeronautics — an  interest  ever  increas- 
ing and  international  in  scope — and  the  recent  discoveries  in  the  atmos- 
phere of  argon,  helium,  and  their  associated  rarer  gases,  accentuate  the 
fact  that  the  present  information  regarding  the  oxygen  content  of  atmos- 
pheric air,  and,  indeed,  of  the  carbon-dioxide  content,  is  far  from  satis- 
factory. The  known  sources  of  oxygen  are  very  limited  in  number,  for 
although  it  has  been  demonstrated  that  during  certain  periods  of  vege- 
tative growth  oxygen  is  liberated,  the  amount  thus  supplied  to  the  atmos- 
phere must  of  necessity  be  slight.  On  the  other  hand,  the  drafts  upon 
atmospheric  oxygen  are  constantly  increasing.  Taking  into  considera- 
tion those  agencies  that  are  directly  or  indirectly  influenced  by  man,  we 
see  that  since  both  the  population  of  the  world  and  the  combustion  of 
fuel  are  increasing  enormously,  this  drain  upon  atmospheric  oxygen  must 
to-day  be  very  much  greater  than,  for  instance,  during  the  Stone  Age.  If, 
in  addition,  we  consider  the  abstraction  of  oxygen  by  living  organisms 
other  than  man,  the  oxidation  of  organic  matter  and  decay,  and  the  oxida- 
tion of  iron,  we  find  that  all  doubtless  play  an  important  role  in  decreasing 
the  percentage  of  oxygen  in  the  air.  With  these  various  agencies  at  work 
diminishing  oxygen  and  producing  carbon  dioxide,  it  is  to  be  expected 
that  variations  in  the  density  of  population,  in  the  number  of  factories, 
in  the  distribution  of  vegetative  tracts,  and  in  the  proportion  of  land  and 
sea,  would  lead  to  like  variations  in  the  composition  of  the  air.  The  near- 
est analogy  to  the  atmosphere  is  sea-water,  which,  while  vast  in  bulk,  is 
known  to  have  differences  in  composition  at  different  depths  and  with 
different  geographical  distribution. 

If  changes  take  place  in  the  composition  of  the  air,  of  what  nature  are 
they?  Are  they  measurable  by  our  present  methods  of  chemical  analysis? 
Do  these  variations  bear  any  relation  to  the  changing  seasons,  to  growth 
of  vegetation,  to  rain,  snow,  and  similar  meteorological  conditions,  and  to 
geographical  location?  These  are  questions  that  have  long  been  in  the 
minds  of  scientists,  and,  indeed,  are  to-day  still  debatable. 

Alterations  in  climatic  conditions  have  been  ascribed  by  Arrhenius* 
to  relatively  small  changes  in  the  carbon-dioxide  content  of  the  air.  Thus 
it  seems  that  on  meteorological  grounds  alone  a  study  of  the  composition 

*  Arrhenius,  Philosophical  Magazine,  1896,  pp.  237-276;  also,  Svenska  Veten8kai>s- 
Akademiens  Forhandlingar,  1901, 58,  pp.  25-58. 

3 


4  Composition  of  the  Atmosphere 

of  air  is  well  worth  undertaking.  But  such  a  study,  especially  the  study 
of  the  oxygen  content  of  the  air,  has  a  still  higher  value  in  its  relation  to 
human  life.  No  one  chemical  element  enters  so  extensively  into  vital 
processes  as  does  oxygen.  The  human  body  may  live  without  food  for 
many  weeks;  it  may  live  without  water  for  several  days;  but  without  air 
or  oxygen  it  can  live  for  only  a  very  few  minutes.  Not  only  is  oxygen  es- 
sential to  life,  but  the  purity  of  the  air  is  of  fundamental  hygienic  impor- 
tance. That  this  fact  has  been  recognized  is  evidenced  by  the  emphasis 
recently  laid  upon  the  necessity  of  an  outdoor  existence  in  combating  tu- 
berculosis. Furthermore,  a  knowledge  of  the  composition  of  the  air  is 
necessary  for  the  solution  of  the  important  problems  of  the  ventilation  of 
houses,  mines,  rapid-transit  subways,  and  railroad  tunnels.  Of  still  more 
special  significance,  and  with  a  more  intimate  bearing  upon  problems  in 
physiology,  is  the  fact  that  the  determination  of  the  oxygen  consumption 
of  man  and  important  quantitative  determinations  in  respiration  experi- 
ments depend  usually  upon  an  exact  knowledge  of  the  composition  of  the 
air  taken  into  the  lungs.  It  is  peculiarly  fitting,  therefore,  that  a  study 
of  this  subject  should  be  made  a  part  of  the  scheme  of  research  carried  out 
in  the  Nutrition  Laboratory. 

The  two  forms  of  gas-analysis  apparatus  conceded  by  all  experimenters 
to  give  the  most  exact  results  are  the  apparatus  of  Haldane  in  England 
and  that  of  Sonden  and  Pettersson  in  Stockholm.  Several  forms  of  the 
Haldane  apparatus  are  in  the  possession  of  the  Nutrition  Laboratory,  and 
also  a  Sonden  apparatus  specially  designed  for  the  determination  of  carbon 
dioxide  and  oxygen  in  the  air  of  the  respiration  chamber.  This  latter 
apparatus  was  devised  by  Dr.  Sonden  after  a  conference  with  the  author 
in  Stockholm  four  years  ago,  in  which  the  various  difficulties  in  the  way  of 
exact  gas-analysis  were  carefully  considered.  With  this  apparatus  the 
Nutrition  Laboratory  found  itself  in  a  position  to  carry  out  a  more  com- 
plete study  of  the  percentage  of  oxygen  in  outdoor  air  than  had  hitherto 
been  made.  The  ingenuity  of  Dr.  Sonden  and  the  technical  skill  of 
Miss  Alice  Johnson,  of  the  laboratory  staff,  made  such  a  study  of  atmos- 
pheric oxygen  possible. 

EARLY  INVESTIGATIONS  ON  THE  COMPOSITION  OF  AIR. 

Although  much  has  been  written  in  recent  years  regarding  the  chemi- 
cal composition  of  the  atmosphere,  there  exists  nowhere,  at  least  in  Eng- 
lish, an  historical  account  of  the  development  of  knowledge  regarding  the 
percentage  of  oxygen  in  the  air;  it  is  therefore  deemed  fitting  to  collect 
in  this  memoir  the  widely  scattered  records  of  the  development  of  this 
most  interesting  subject. 

The  tenacity  with  which  the  belief  in  the  elemental  nature  of  air  was 
held  is  well  exemplified  by  the  fact  that  not  until  the  latter  part  of  the 
eighteenth  century  did  scientists  begin  to  appreciate  the  fact  that  air  con- 
sisted of  two  or  more  gases.     This  recognition  of  the  composition  of  air 


History  of  Air-Analysis  5 

was  unquestionably  much  retarded  by  the  general  acceptance  of  the  phlo- 
giston theory  advocated  by  Stahl.  According  to  the  supporters  of  the 
phlogiston  theory,  all  air  had  the  same  composition,  but  was  more  or 
less  supplied  with  the  "  combustible  essence  "  phlogiston.  As  a  matter 
of  fact,  we  find  that  the  earliest  investigators  whose  experimental  evi- 
dence subsequently  showed  air  to  be  composed  of  two  or  more  gases, 
namely,  Scheele,  Priestley,  Cavendish,  and  Lavoisier,  all  firmly  beUeved 
in  the  phlogiston  theory.  Even  after  numerous  roughly"  quantitative 
experiments  had  been  made  in  which  it  had  been  demonstrated  that  the 
volume  of  air  decreased  after  oxidation  of  material  in  it,  scientists  were 
loath  to  give  up  the  phlogiston  theory,  and  air  was  said  to  be  more  or  less 
phlogisticated.  Although  a  diminution  in  volume  was  observed  when  air 
was  exposed  to  certain  substances,  such  as  alkaline  sulphides,  moist  iron 
filings,  phosphorus,  or  nitric  oxide,  this  loss  was  simply  considered  as  due 
to  a  portion  of  the  atmosphere  which  was  not  saturated  with  phlogiston. 

Scheele,  noting  the  fact  that  the  specific  gravity  of  the  air  after  ab- 
sorption by  various  reagents  had  not  altered,  concluded  that  the  decrease 
in  bulk  could  not  be  due,  as  he  first  supposed,  to  the  absorption  of  phlo- 
giston, and  that  the  atmosphere  must  of  necessity  consist  of  two  distinct 
fluids.  Although  at  first  a  strong  supporter  of  the  phlogiston  theory, 
Lavoisier  in  1777  enunciated  the  belief  that  the  air  consisted  of  two  gases, 
one  nitrogen  (azote)  and  the  other  at  first  called  dephlogisticated  air,  but 
finally  known  as  oxygen;  thus,  for  the  first  time,  the  definite  existence  of 
two  distinct  elemental  components  of  the  atmosphere  was  made  clear. 
This  observation  soon  led  Lavoisier  to  the  belief  that  all  the  phenomena  of 
combustion  could  be  explained  on  the  basis  of  oxygenation  without  refer- 
ence to  the  existence  of  phlogiston.  Cavendish  did  not  accept  this  new 
conception  of  the  composition  of  the  air  until  a  number  of  years  later, 
and  even  then  his  acceptance  was  far  from  a  complete  surrender.  The 
one  man,  Priestley,  who,  perhaps  more  than  anyone  else,  illuminated  our 
knowledge  of  the  atmosphere  by  his  discovery  of  oxygen,  advocated  the 
phlogiston  theory  until  his  death  in  1810. 

It  is  thus  clear  that  the  dephlogisticated  air  of  the  earlier  scientists  was 
nothing  more  nor  less  than  what  we  now  call  oxygen,  and  hence,  although 
many  of  these  writers  considered  the  diminution  in  volume  produced  by 
the  various  reagents  as  an  index  of  the  amount  of  dephlogisticated  air 
present,  their  observations  have  a  certain  historical  value  as  indicating 
approximately  the  estimation  of  the  amount  of  oxygen  in  the  air  by  the 
methods  then  current. 

The  earliest  observations  of  the  quantitative  relationship  between  the 
dephlogisticated  air  and  the  phlogisticated  air  were  undoubtedly  made 
simultaneously  by  Priestley  in  England  and  Scheele  in  Sweden.  ^   Scheele's 

^  According  to  the  published  notebooks  and  laboratory  records  of  Scheele  (Carl  Wil- 
helm  Scheele,  Efterlemnade  bref  och  anteckningar,  Utgifna  af  A.  E.  Nordenskiold, 
Stockholm,  1892),  his  experiments  must  have  antedated  Priestley  by  two  or  three  years. 


6  Composition  of  the  Atmosphere 

experiments  were  wonderfully  comprehensive  and  included  a  determina- 
tion of  the  decrease  in  volume  of  a  confined  mass  of  air  not  only  when 
mixed  with  nitric  oxide  but  when  subjected  to  the  action  of  alkaline  sul- 
phides, moist  iron  filings  with  and  without  a-n  admixture  of  sulphur,  phos- 
phorus ignited  and  at  room  temperature,  and  precipitated  ferrous  hy- 
droxide. His  experiments  with  alkaline  sulphides  w^ere  somewhat  more 
extensive  than  with  the  other  agents.  In  the  first  experiment  he  dissolved 
alkaline  liver  of  sulphur  in  water,  poured  4  ounces  of  the  solution  into  a 
24-ounce  bottle,  which  he  corked  well,  then  reversed  the  bottle,  and  im- 
mersed its  neck  in  a  small  vessel  of  water,  keeping  it  in  this  position  for  a 
fortnight.  At  the  end  of  this  time,  without  removing  the  bottle  from  the 
water,  he  took  out  the  cork,  and  the  water  at  once  rushed  into  the  bottle. 
By  noting  the  amount  of  water  thus  added  he  was  able  to  demonstrate 
that  in  a  fortnight,  out  of  the  20  volumes  of  air  in  the  bottle,  6  volumes 
were  lost.  In  a  second  experiment  he  reports  that  4  parts  were  lost  out 
of  20,  and  at  another  time,  when  the  bottle  was  corked  for  4  months,  there 
were  6  parts  lost  out  of  20.  As  the  result  of  the  third  experiment  agreed 
with  the  first,  the  average  of  the  three  experiments  shows  a  loss  of  approxi- 
mately 6  parts  out  of  20,  or  30  per  cent.  Scheele  also  exposed  phosphorus 
to  a  confined  volume  of  air,  allowing  it  to  remain  for  6  weeks,  and  found 
that  one-third  of  the  air  was  lost. 

Of  particular  significance  in  the  light  of  the  main  purpose  of  this  mem- 
oir is  the  fact  the  Scheele  was  the  first  to  attempt  a  systematic  study  of  the 
composition  of  the  atmosphere  over  a  lengthy  period.  In  1779  he  com- 
municated to  the  Academy^  in  Stockholm  the  results  of  his  investigation 
of  the  preceding  year.  This  communication  was  deemed  of  great  impor- 
tance by  Lavoisier. 2 

The  method  employed  by  Scheele  was  to  expose  a  confined  volume  of 
air  to  the  action  of  a  mixture  of  2  parts  of  iron  filings  and  1  part  of  pow- 
dered sulphur,  to  which  had  been  added  a  small  amount  of  water.  This 
mixture  produced  in  a  few  hours  a  diminution  of  the  air  greater  than  that 
obtained  by  the  sulphuret  of  potassium  in  several  days.^  Scheele  used 
this  method  to  determine  the  degree  of  salubrity  of  the  atmosphere  at 
different  times  of  the  year  and  to  find  out  the  proportion  of  ''vital"  air. 

From  January  1  to  March  23,  1778,  atmospheric  air  was  found  to  con- 
tain 27.3  per  cent  of  oxygen;  on  March  23,  24.2  per  cent;  on  April  19,  20, 
and  21,  30.0  per  cent.  During  the  months  of  May  and  June  the  quantity 
of  vital  air  was  between  24  and  27  per  cent;  on  October  5,  during  a  very 
heavy  storm,  it  was  found  to  be  30  per  cent.  From  October  5  to  Novem- 
ber 4  the  quantity  of  vital  air  was  24  to  27  per  cent;  and  on  November  4 
and  5,  with  the  barometer  very  high,  it  was  24  per  cent.    From  November 

*  Scheele,  Kongl.  Vetenskaps-Academiens  Handlingar,  1779,  40,  p.  50. 

*  Lavoisier,  Recueil  des  Memoires  de  Lavoisier,  3,  p.  154;  and  Oeuvres  de  Lavoisier, 
1862,  2,  p.  715. 

*  A  figure  of  Scheele's  apparatus  is  also  given  in  F.  Hoefer's  Histoire  de  la  chimie,  2d 
ed.,  Paris,  1869, 2,  p.  456. 


History  of  Air-Analysis  7 

5  to  20,  the  quantity  of  vital  air  was  24  to  27  per  cent;  on  November  20 
30  per  cent,  and  on  November  21,  24  per  cent.  During  December  the 
quantity  of  vital  air  was  constantly  between  24  and  27  per  cent. 

Scheele's  investigation  slowly  but  surely  claimed  the  attention  of 
scientists  in  other  countries.  In  this  connection  it  is  of  interest  to  quote 
the  words  of  Dr.  Joseph  Black  :^ 

But  Scheele  was  the  first  person  who,  from  a  number  of  ingeniously  contrived  ex- 
periments, concluded  by  very  fair  reasoning  that  atmospherical  air  is  a  mixed  fluid 
composed  of  about  two  parts  of  azotic  gas,  and  one  part  of  vital  air  or  oxygen  gas,  along 
with  a  very  small  admixture  of  carbonic  acid. 

The  ingenuity  and  industry  of  this  great  Swede  may  properly  be  con- 
sidered as  having  started  the  investigation  of  the  composition  of  the  airm- 
an investigation  that  has  had  almost  the  continuous  attention  of  chemists 
for  over  130  years. 

THE  NITRIC-OXIDE   EUDIOMETER. 

Contemporaneously  with  Scheele,  Priestley  in  England  published  sev- 
eral volumes  of  his  "Observations  on  Air."  In  1772  Priestley  observed 
that  when  nitric  oxide,  prepared  a  number  of  years  before  by  Stephen 
Hales,  was  added  to  common  air  confined  in  a  vessel  over  water,  a  diminu- 
tion in  volume  resulted.  Experimenting  in  this  way,  Priestley  showed 
that  about  one-fifth  of  the  air  combined  with  the  nitric  oxide  and  was  ab- 
sorbed by  the  water.  ^ 

Priestley's  discovery  of  oxygen,  which  he  found  by  heating  the  red  ox- 
ide of  mercury,  was  made  on  August  1,  1774.  He  was  so  wedded  to  the 
phlogiston  theory,  however,  that  he  could  only  consider  this  oxygen  as 
dephlogisticated  air;  hence  its  elemental  nature  was  never  admitted  by 
him.  This  discovery  was  shortly  followed  by  researches  on  the  relation- 
ship between  oxygen  and  the  vital  processes.  It  was  early  believed  that 
the  vital  processes  were  more  active  in  oxygen-rich  air  than  in  air  that  was 
deficient  in  oxygen;  this  stimulated  innumerable  investigations  of  the 
purity  or  salubrity  of  the  air,  chiefly  by  means  of  the  simple  nitric-oxide 
reaction  of  Priestley.  The  attempts  to  measure  quantitatively  the  oxy- 
gen in  the  air  early  led  to  the  development  of  special  forms  of  apparatus 
for  these  measurements ;  as  a  matter  of  fact  so  extensively  was  the  nitric- 
oxide  test  employed  for  studying  the  oxygen  content  of  air,  and  so  univer- 
sal was  the  belief  that  the  larger  the  amount  of  oxygen  in  the  air  the  better 
was  the  air,  that  the  instrument  was  actually  designated  an  eudiometer, 
i.e.,  a  measurer  of  the  goodness  or  salubrity  of  the  air.  As  the  dephlogisti- 
cated air  supported  respiration  and  combustion  much  better  than  ordi- 
nary air,  it  was  natural  to  ascribe  the  healthfulness  of  the  latter  to  the 
amount  of  dephlogisticated  air  present  in  it. 

1  Black,  Lectures  on  the  elements  of  chemistry,  1st  Am.  ed.  from  the  last  London  ed., 
1806,  2,  p.  344.  See  also  Scheele,  Efterlemnade  bref  och  anteckningar,  edited  by  A.  E. 
Nordenskiold,  Stockholm,  1892,  p.  78. 

*  Priestley,  Experiments  and  observations  on  different  kinds  of  air,  1775,  1,  p.  111. 


8  Composition  of  the  Atmosphere 

In  considering  the  heterogeneous  results  reported  by  Priestley,  it  is 
important  to  note  that  the  values  he  obtained  were  all  comparative  rather 
than  absolute.  He  supposed  that  all  samples  of  air  had  different  quan- 
tities of  dephlogisticated  air  in  them;  and  if  he  took  one  sample  of  good  air, 
compared  it  with  a  sample  of  questioned  purity  taken  at  the  same  time 
and  at  another  place,  and  found  that  they  underwent  the  same  contrac- 
tion in  volume,  he  could  assume  that  the  two  samples  were  equally  pure. 
In  other  words,  Priestley  evidently  failed  to  realize  the  significance  of  the 
contraction  in  volume.  All  of  the  observations  of  Priestley,  then,  were 
made  distinctly  upon  the  comparative  rather  than  upon  the  absolute  ba- 
sis. He  was,  indeed,  somewhat  disturbed  by  the  fact  that  air  which  theo- 
retically was  bad  did  not  often  show  any  deterioration.^  He  says  on  this 
point: 

^^■hen  I  first  discovered  the  property  of  nitrous  air  as  a  test  of  the  wholesomeness  of 
oonmiOD  air,  I  flattered  myself  that  it  might  be  of  considerable  practical  use,  and  par- 
ticularly that  the  air  of  distant  places  and  countries  might  be  brought  and  examined  to- 
gether with  great  ease  and  satisfaction;  but  I  own  that  hitherto  I  have  been  rather 
disappointed  in  my  expectations  from  it.  My  own  observations  have  not,  indeed,  been 
many;  but  according  to  them  the  diflFerence  of  the  open  air  in  different  places,  as  indicated 
by  a  mixture  of  nitrous  air,  is  generally  inconsiderable;  and  I  have  reason  to  think  that 
when  very  unwholesome  air  is  conveyed  to  a  great  distance,  and  much  time  elapses  before 
it  is  tried,  it  approaches,  by  some  means  or  other,  to  the  state  of  wholesome  air.  At 
least  such  I  have  found  to  be  the  case  with  the  worst  air  that  has  at  any  time  been  sent 
to  me  in  Wiltshire  from  distant  manufacturing  towns  and  workshops,  etc.,  in  them,  where 
the  air  was  thought  to  be  pecuUarly  unwholesome.  I  am  satisfied,  however,  from  my 
own  observations,  that  air  may  be  very  offensive  to  the  nostrils,  probably  hurtful  to  the 
lungs,  and  perhaps  also  in  consequence  of  the  presence  of  phlogistic  matter  in  it,  without 
the  phlogiston  being  so  far  incorporated  with  it,  as  to  be  discoverable  by  the  mixture 
of  nitrous  air. 

I  gave  several  of  my  friends  the  trouble  to  send  me  air  from  distant  places,  especially 
from  manufacturing  towns,  and  the  worst  they  could  find  to  be  actually  breathed  by  the 
manufacturers,  such  as  is  known  to  be  exceedingly  oflFensive  to  those  who  visit  them;  but 
when  I  examined  those  specimens  of  air  in  Wiltshire,  the  difference  between  them  and 
the  very  best  air  in  this  country,  which  is  esteemed  to  be  very  good,  as  also  the  difference 
between  them  and  specimens  of  the  best  air  in  the  counties  in  which  those  manufacturing 
towns  are  situated,  was  very  trifling. 

Mr.  S.  Vaughan,  senior,  on  his  passage  from  Jamaica,  brought  me  two  bottles  of  air, 
one  from  the  hold  of  the  ship,  intolerably  offensive,  the  other  the  fresh  air  above  deck 
in  about  30'  N,;  but  the  difference  between  these  specimens  of  air,  and  the  air  of  Wilt- 
shire, was  quite  inconsiderable. 

I  have  frequently  taken  the  open  air  in  the  most  exposed  places  in  this  country  at 
different  times  of  the  year,  and  in  different  states  of  the  weather,  etc.,  but  never  found 
the  difference  so  great  as  the  inaccuracy  arising  from  the  method  of  making  the  trial 
might  easily  amount  to,  or  exceed. 

This  recognition  of  at  least  the  existence  of  a  limit  of  accuracy  for  his 
method  was  unfortunately  not  seriously  considered  by  many  of  his  con- 
temporaries. 

»  Priestley,  loc.  cit.,  1779,  4,  p.  269. 


History  of  Air-Analysis  9 

The  application  of  the  nitrous-oxide  method  for  determining  the  degree 
of  phlogistication  of  the  air  as  first  brought  out  by  Priestley  immediately 
led  to  an  extensive  interest  in  this  problem  on  the  part  of  a  number  of  in- 
vestigators. As  Priestley's  observations  were  but  roughly  quantitative, 
the  Abbe  Felice  Fontana^  in  Italy  constructed  an  instrument  permitting 
a  much  greater  accuracy  in  the  measurement  of  the  contraction  in  volume 
and  determined  the  quantity  of  oxygen  contained  in  air  by  absorption 
with  nitric  oxide,  obtaining  results  showing  from  18  to  25  per  cent.  Using 
this  instrument,  a  number  of  investigators  began  studying  the  absorption 
due  to  nitric  oxide,  an  absorption  that  was  shortly  to  be  explained  by  the 
oxygenation  theory  of  Lavoisier.  Slight  minor  modifications  of  the  ap- 
paratus and  method  were  made  by  many  scientists  who  appeared  almost 
inordinately^  occupied  in  the  testing  of  air  in  various  places. 

Prominent  among  the  users  of  this  instrument  was  Marsiglio  Lan- 
driani,^  who  in  1775  published  a  record  of  his  investigation  and  first  in- 
troduced the  term  ''eudiometer,"  descriptive  of  the  instrument  devised  by 
Fontana. 

In  a  letter  to  Priestley,  dated  at  Milan,  November  17, 1776,^  Landriani 
writes : 

Before  you  receive  this  letter  I  shall  have  sent  you  my  eudiometer,  together  with  a 
short  memoir,  explaining  the  use  of  the  machine,  in  order  to  ascertain  with  exactness  the 
wholesomeness  of  the  air  in  any  particular  place.  It  is  the  same  instrument  that  I  made 
use  of  in  my  tour  through  Italy,  in  the  course  of  which  I  have  had  the  satisfaction  of 
convincing  myself  that  the  air  of  all  those  places  which,  from  the  long  experience  of  the 
inhabitants,  has  been  reputed  unwholesome,  is  found  to  be  so,  to  a  very  great  degree  of 
exactness,  by  this  instrument  of  mine,  so  that  the  theory  seems  to  correspond  very  well 
to  observation.  In  the  mountains  near  Pisa  I  made  trial  of  the  air  at  different  heights, 
beginning  on  the  plain,  and  proceeding  to  the  highest  summits;  and  found  a  remarkable 
difference  in  the  state  of  the  air,  every  stratum  being  purer  in  proportion  as  I  ascended. 

^  Felice  Fontana,  Descrizioni  ed  usi  di  alcuni  stromenti  per  misurar  la  salubritd  dell' 
aria,  Firenze,  1774. 

2  For  20  to  30  years  after  Priestley's  first  discovery  of  the  nitric-oxide  eudiometer,  it 
would  appear  from  the  innumerable  references  in  the  literature  that  every  scientist  of 
reputation,  and  many  with  no  reputation,  attempted  air-analyses.  Writing  in  1912, 
one  can  but  compare  proportionally  the  number  of  those  using  the  various  forms  of  eu- 
diometer 130  years  ago  with  those  to-day  using  wireless  telegraphic  apparatus.  Priest- 
ley has  summed  up  the  situation  admirably  in  the  following  sentences  from  the  preface 
to  volume  3  of  his  "Experiments  and  observations  on  different  kinds  of  air,"  1777: 

^  "Those  of  my  readers  who  may  wish  that  I  would  still  give  a  principal  attention  to 
this  branch  of  experimental  philosophy,  will  the  less  regret  my  discontinuing  it,  when 
they  are  informed  with  how  much  ardour  and  ability  these  pursuits  are  now  prosecuted 
in  very  different  parts  of  Europe. 

"I  am  also  informed  by  my  friend  Mr.  Magellan,  who  frequently  visits,  and  has  a 
very  extensive  correspondence  with  the  Continent,  so  as  to  be  well  acquainted  with  the 
present  pursuits  of  philosophers,  and  who  has  himself  taken  pains  to  instruct  many  in- 
genious foreigners  in  the  best  methods  of  making  experiments  of  this  kind,  that  many 
other  persons,  whose  names  are  at  present  unknown  to  the  public,  are  at  this  very  time 
assiduously  employed  on  the  same  subject." 

See  also  Johann  Andreas  Scherer,  Geschichte  der  Luftgiitepriifungslehre,  Vienna, 
1785,  2,  p.  74. 

2  Marsiglio  Landriani,  Richerche  fisiche  intomo  alle  salubritd,  dell'  aria,  Milano,  1775. 

*  Translated  and  printed  in  Priestley's  Experiments  and  observations  on  different 
kinds  of  air,  1777,  3,  p.  380. 


10  Composition  of  the  Atmosphere 

Among  other  early  modifications  of  the  nitric-oxide  eudiometer  are 
those  of  Magellan.^  These  are  also  referred  to  in  a  postscript  in  a  letter 
to  Priestley,*  dated  London,  November  30, 1776,  in  which  he  writes: 

The  other  contrivances  I  want  to  show  you  are  two  new  eudiometers  to  measure  the 
degree  of  the  salubrity  of  the  air  in  different  places.  One  of  them,  which  I  reckon  the 
better,  being  the  more  simple  and  the  neater  of  the  two,  is  according  to  the  original 
idea  of  your  experiments  on  this  subject;  but  in  neither  of  them  do  I  make  use  of  any 
cock,  both  on  account  of  its  being  diflficult  to  be  made,  and  Ukewise  subject  to  be  out  of 
order.  Those  of  Mess,  the  Chevalier  Landriani  and  the  Abb6  Fontana  seem  to  be  liable 
to  this  inconvenience.  The  experiments  already  made  in  most  parts  of  Italy  by  the 
former  of  those  gentlemen,  with  his  own  eudiometer,  deserve  the  greatest  praises;  and 
it  is  to  be  wished  that  philosophers  would  more  generally  apply  themselves  to  this  inter- 
esting subject  of  inquiry. 

Dobson's^  instrument  was  used  for  analyzing  the  air  of  "sea  weed 
pods"  and  also,  for  comparison,  the  air  of  Liverpool. 

Lavoisier*  reports  three  experiments  made  with  nitric  oxide  in  which 
he  found  25.3,  25,  and  25.2  per  cent  of  oxygen,  respectively,  an  agreement 
which  he  says  he  had  not  dared  to  hope  for.  From  these  results,  thcFefore, 
he  concludes  that  the  atmosphere,  as  he  had  previously  announced,  con- 
sisted of  about  3  parts  of  mephitic  air  and  1  part  of  vital  air.  In  1777 
Lavoisier  made  determinations  of  the  quantity  of  vital  air  contained  in 
the  atmosphere  and  found  it  to  be  about  27.5  parts  in  100,  but  maintains 
it  is  possible  that  this  larger  quantity  of  vital  air  depends  upon  the  season. 

Undoubtedly  this  quest  for  air  with  the  highest  oxygen  content  led  to 
innumerable  analyses  of  atmospheric  air  in  the  latter  part  of  the  eight- 
eenth century  which  otherwise  would  not  have  been  made.  We  find  that 
Cavendish  is  reported  as  having  made  over  500  analyses  of  air  by  the 
nitric-oxide  eudiometer  before  1790.^  Similarly  the  method  was  employed 
''daily  for  three  years"  by  de  Saussure*'  in  a  comparison  of  this  method 
with  the  phosphorus  eudiometer  which  was  later  to  play  an  important  r61e 
in  air-analyses. 

While  many  observers  early  found  diflaculties  in  the  nitric-oxide 
method  and  soon  discarded  it  for  other  methods,  it  seems  to  have  been 
reserved  for  the  genius  of  Cavendish  so  to  adjust  the  conditions  of  experi- 
mentation with  this  agent  as  to  secure  approximately  accurate  infor- 
mation regarding  the  proportion  of  oxygen  and  nitrogen  in  the  air.  His 
results  are  marvelously  accurate  when  judged  by  analyses  made  by  the 
most  approved  methods  of  modern  times.     Cavendish  was  more  interested 

Z*^'  ,?Jy^,<iy°^h  de  Magellan,  Description  of  a  glass  apparatus  for  making  mineral 
waters  Uke  those  of  Pyrmont  Spa,  Seltzer,  Seydschnitz,  etc.,  together  with  the  descrip- 
Uon  of  some  new  eudiometers,  etc.,  London,  1777. 

«  Priestley,  loc.  cit.,  1777, 3,  p.  379. 

•See  Dobson's  letter  to  Priestley,  loc.  cit.,  1779, 4,  p.  469. 
deLa^TSeri862T°^^503^^  I'Academie  des  Sciences,  1782,  p.  486.    See  also  Oeuvres 

•  Wilson,  Life  and  works  of  Cavendish,  London,  1851,  p.  227. 
derPhylkT799'/°''S5  ^^  ^^y^'"*^®'  ^™'  ^7'  P'  ^^O.    See  also  Gilbert's  Annalen 


History  of  Air- Analysis  11 

in  knowing  the  amount  of  the  decrease  in  volume  than  the  cause.  With 
his  keen  insight  and  experimental  technique  he  attacked  the  problem,  and 
in  1783  published  a  paper  describing  a  new  eudiometer.  By  carefully 
noting  the  rate  and  the  amount  of  nitric  oxide  used  with  this  apparatus 
and  particularly  by  adding  the  air  to  a  previously  measured  amount  of 
nitric  oxide,  he  was  able  to  make  a  more  careful  examination  and  test  of 
air.  Of  particular  interest  in  connection  with  this  paper  are  his  words 
regarding  the  tests  of  air  on  different  days  :^ 

During  the  last  half  of  the  year  1781 1  tried  the  air  of  near  60  different  days  in  order 
to  find  whether  it  was  sensibly  more  phlogisticated  at  one  time  than  another;  but  found 
no  difference  that  I  could  be  sure  of,  though  the  wind  and  weather  on  those  days  were 
very  various,  some  of  them  being  very  fair  and  clear,  others  very  wet,  and  others  very 
foggy. 

He  also  studied  the  air  in  different  localities  and  compared  the  air  of 
London  with  that  of  the  country.  Although  Cavendish  found  some  evi- 
dence to  show  that  the  air  at  Kensington  was  better  than  that  in  London, 
he  nevertheless  believed  that  the  differences  were  no  greater  than  the 
limits  of  experimental  error,  and  taking  the  mean  of  all,  that  there  was 
apparently  no  difference  between  them.  The  number  of  days  compared 
was  20,  the  greater  part  of  the  samples  being  taken  in  cold  winter  weather, 
when  there  were  a  great  many  fires  and  but  little  wind  to  blow  away  the 
smoke.  From  figures  given  in  Cavendish's  notebook,  Wilson^  concluded 
that  these  observations  established  that  the  percentage  of  oxygen  in  the 
air  was  20.83.  This  figure  has  been  made  much  of  in  discussions  of  the 
percentage  of  oxygen  in  the  air,  but  an  examination  of  Cavendish's  data 
shows  that  the  limit  of  error  was  very  large,  and  that  he  could  not  possibly 
have  been  inside  of  1  or  2  per  cent  of  the  total  amount  of  oxygen  involved ; 
hence  a  representation  of  his  percentage  of  oxygen  with  four  significant 
figures  is  without  value.  As  Cavendish  at  that  time  paid  no  attention  to 
the  purity  of  the  nitric  oxide,  although  recognizing  in  a  crude  way  the  dif- 
ferences in  quality  and  the  possibility  of  combination  with  varying  amounts 
of  dephlogisticated  air  or  oxygen,  it  is  fair  to  conclude  that  the  method 
could  not  possibly  have  had  an  accuracy  closer  than  2  per  cent  of  the  total. 
Cavendish  was  the  first  to  establish  that  the  composition  of  the  air  was 
essentially  constant  within  the  limits  of  his  apparatus,  and  that  it  did  not 
sensibly  vary  in  different  parts  of  the  country.  That  it  was  possible 
to  obtain  these  results  with  an  instrument  and  a  method  with  as  great 
error  as  we  now  know  them  to  have  had  is  certainly  most  remarkable  evi- 
dence of  his  skill  as  an  experimenter. 

Among  others  who  extensively  used  the  nitric-oxide  eudiometer  must 
be  mentioned  Ingen-housz,  who,  in  his  researches  on  plant  life  and  on  his 
travels,  used  a  portable  apparatus  of  his  own  devising.' 

*  Cavendish,  Philosophical  Transactions,  1783,  73,  p.  126. 

*  Wilson,  loc.  cit.,  p.  41. 

'  Ingen-housz,  Vermischte  Schriften,  2d  ed.,  Vienna,  1784, 2,  p.  242. 


12  Composition  of  the  Atmosphere 

Van  Breda^  in  Delft  made  analyses  of  air  by  the  nitric-oxide  eudiom- 
eter on  195  days  in  1781  and  1782,  but  the  results  have  little  quantitative 
value. 

In  an  address  before  the  Academy  in  Barcelona  on  May  22,  1790,  An- 
tonio de  Marti^  announced  the  results  of  his  experiments  on  the  "Quan- 
tity of  vital  air  in  the  atmosphere,  and  the  different  methods  of  measuring 
it."  Among  other  means  he  used  nitric  oxide  and  reported  uniformity  in 
composition  of  the  air. 

During  some  days  of  the  year  1787,  in  which  the  common  air  experienced  no  varia- 
tion by  means  of  nitrous  air,  since  100  parts  of  each  were  uniformly  reduced  to  99  or  00, 
I  was  desirous  of  making  a  comparative  trial  of  the  same  common  air  by  means  of  iron 
and  sulphur,  and  I  observed  that  of  100  parts  of  air  there  remained  from  79  to  81  and 
that  consequently,  from  19  to  21  hundredths  had  disappeared. 

One  of  the  most  extensive  contributors  to  our  knowledge  of  the  com- 
position of  the  air  obtained  by  means  of  the  nitric-oxide  eudiometer  was 
Alexander  von  Humboldt,  and  in  his  records  we  find  recognition  of  the 
existence  not  of  dephlogisticated  air  but  of  oxygen,  accepting  Lavoisier's 
newest  theory  with  regard  to  the  air.  von  Humboldt  recognized  the  im- 
portance of  testing  the  purity  of  the  nitric  oxide  used,  and  determined 
the  degree  to  which  it  would  dissolve  in  a  ferrous-sulphate  solution. 

In  1798  von  Humboldt'  had  analyzed  the  air  collected  in  a  balloon 
journey  by  Garnerin  and  Beauvais  at  an  altitude  of  1303  meters  and  com- 
pared it  with  the  air  of  Paris,  using  nitric  oxide  and  ferrous  sulphate. 
The  air  in  Paris  showed  27.6  per  cent  oxygen  and  the  balloon  air  25.9  per 
cent.  These  balloon  samples  are  of  general  interest  in  that  they  sub- 
stantiate the  simultaneous  observations  of  de  Saussure,^  who,  using  a 
nitric-oxide  eudiometer,  analyzed  air  taken  from  the  tops  of  several  moun- 
tains. Though  the  results  are  not  expressed  numerically,  de  Saussure 
concludes  that  the  air  of  mountains  is  somewhat  less  pure  in  vital  air 
than  that  of  the  neighboring  plains  and  valleys. 

Although  a  large  number  of  desultory  investigations  had  been  made  by 
Ingen-housz  in  London,  van  Breda  in  Delft,  Pickel  in  Wurzburg,  Lam- 
padius  in  Freiburg,  Lichtenberg  in  Gottingen,  Scherer  in  Vienna,  and 
Breze,  all  of  whom  used  the  nitric-oxide  eudiometer,  yet  von  Humboldt^ 
was  dissatisfied  with  these  researches,  beUeving  that  analyses  of  the  air 
should  be  accompanied  by  observations  with  regard  to  its  elasticity,  tem- 
perature, moisture,  electricity,  and  clearness.  He  accordingly  undertook 
an  extensive  series  of  observations  with  regard  to  the  oxygen  content  of 


»  Letter  to  J.  Ingen-housz,  Vermischte  Schriften,  2d  ed.,  Vienna,  1784,  2,  p.  441. 

« This  lecture  was  translated  into  French  and  printed  in  the  Journal  de  Physique, 
1801,  52,  p.  173.  Abstracted  in  Gilbert's  Annalen  der  Physik,  1805,  19,  p.  389.  The 
lecture  was  also  printed  in  English  in  the  Philosophical  Magazine,  1801,  9,  p.  250. 

» von  Humboldt,  Journal  de  Physique,  1798, 47,  p.  202. 

♦  de  Saussure,  Voyages  dans  les  Alpes,  Neuchatel,  1803,  I ,  p.  427. 

'von  Humboldt,  Versuche  tiber  die  chemische  Zerlegung  des  Luftkreises,  Braun- 
schweig, 1799,  p.  150. 


History  of  Air-Analysis 


13 


air  in  Salzburg,  using  a  nitric-oxide  eudiometer.  The  close  proximity  to 
the  Alps  also  enabled  him  to  study  the  composition  of  air  on  the  top  of 
mountains  as  well  as  that  in  the  valley. 

Although  we  now  know  that  von  Humboldt's  oxygen  determinations 
were  erroneous  owing  to  the  test  used,  namely,  nitric  oxide,  nevertheless 
his  observations  and  the  tabular  statement  of  his  results  have  the  com- 
pleteness which  characterizes  modern  scientific  research,  and  in  many  ways 
the  thoroughness  of  the  investigation  commends  itself  to  modern  workers. 
Using  the  Fontana  eudiometer,  he  made  observations  of  the  air  in  Salz- 
burg (1302  feet  above  sea-level),  covering  practically  a  whole  year,  the 
samples  of  air  being  taken  for  the  most  part  from  a  garden  on  the  south 
side  of  the  city.  Since  this  air  might  be  considered  contaminated,  he 
compared  it  with  that  from  the  open  country  some  distance  from  the  city, 
but  was  never  able  to  detect  any  difference.  The  results  are  expressed  in 
tabular  form  at  the  end  of  his  book,  each  value  representing  the  average  of 
3  to  5  tests. 

The  analysis  of  the  Salzburg  air  gave  a  range  in  oxygen  content  from 
23.6  per  cent  to  29  per  cent.  The  author  concluded  that  the  oxygen  con- 
tent can  vary  5.4  per  cent  and  does  not  always  remain  between  27  and  28 
per  cent.  In  observations  on  144  days  he  found  only  7  times  that  the 
oxygen  rose  above  28. 1  per  cent.     The  average  oxygen  content  was : 


per  cent 

November 25.6 

December 26.8 

January 27.5 

February 27.2 


per  cent 

March 26.9 

April    27.2 

Average 26.8 


He  came  to  the  conclusion  that  in  clear  weather  there  is  an  increase  in 
the  oxygen,  and  as  bad  weather  approaches  there  is  a  decrease. 

He  also  made  comparative  observations  of  mountain  and  valley  air. 
With  the  assistance  of  a  friend,  samples  were  taken  simultaneously  at 
noon  from  the  Geisberg  (3890  feet)  and  from  the  valley.  On  December 
18,  1797,  the  mountain  air  gave  23.6  per  cent  of  oxygen  and  the  valley  air 
26.2,  or  2.6  per  cent  of  oxygen  more  than  the  mountain  air.  On  January 
30,  1798,  another  observation  was  made,  the  results  for  the  mountain  air 
being  26.1,  and  for  the  valley  air,  27.4  per  cent.  On  March  4,  1798, 
another  set  of  samples  gave  for  mountain  air  26.4  and  for  valley  air 
27.3  per  cent.  On  March  11,  1798,  the  results  for  the  two  samples  were 
identical,  namely,  26.4  per  cent. 

Assuming  that  the  nitric  oxide  used  by  earlier  experimenters  was  not 
below  a  certain  degree  of  purity,  von  Humboldt  computed  the  oxygen 
content  of  the  air  in  several  cities  as  follows: 

per  cent 

Vienna 26.1 

Gottingen 26.6 

London    26.9 

^  Florence 25.3 

Delft 27.0 


14  Composition  of  the  Atmosphere 

He  evidently  wished  to  take  into  consideration  not  only  the  tempera- 
ture of  the  air  examined,  but  the  possibility  of  differences  in  expansion, 
and  referred  to  one  of  his  researches  indicating  such  a  difference. 

About  the  time  that  his  book  was  published,  von  Humboldt  started 
on  a  scientific  expedition  to  Spanish  America,  and  in  a  letter  written  by 
him  to  Delam^therie^  from  Cumana,  South  America,  he  shows  his  intense 
interest  in  the  composition  of  the  air,  and  in  the  possible  sources  of  con- 
tamination or  alteration  of  the  oxygen  content,  by  citing  his  experiment 
with  a  sample  of  air  which  he  had  collected  in  a  bottle  from  the  crater  of 
a  volcano.  After  having  determined  the  purity  of  his  nitric  oxide  by 
means  of  ferrous  sulphate,  he  found  only  19  per  cent  of  oxygen  in  this 
sample,  while  at  the  sea-level  the  oxygen  content  was  27.8  per  cent. 
The  idea  of  a  geographical  difference  in  composition  of  the  air  was  also 
evidently  present,  since  he  cites  the  fact  that  he  was  able  to  analyze  the 
air  on  board  ship  with  as  much  ease  as  in  his  laboratory,  and  found  that 
the  sea  air  at  10°  30'  "on  a  beautiful  moonlight  night"  contained  over  30 
per  cent  of  oxygen.  So  firm  was  von  Humboldt's  belief  in  the  nitric-oxide 
eudiometer  that  he  was  in  constant  polemical  discussion  with  BerthoUet 
with  regard  to  the  relatively  new  phosphorus  eudiometer. 

As  facility  in  experimental  technique  was  acquired  by  scientists  in  the 
new  field  of  pneumatic  chemistry,  errors  in  the  nitric-oxide  eudiometer 
were  early  recognized  and  it  is  not  surprising  to  find  Seguin^  stating  that 
this  method  has  20  different  errors.  Even  von  Humboldt,^  its  most  ar- 
dent supporter,  pointed  out  that  nitric  acid  of  different  strengths  yielded 
nitric  oxide  of  different  character  which  combined  with  different  amounts 
of  oxygen  from  the  air.  A  few  years  later*  he  acknowledged  completely 
the  errors  of  the  method,  which  he  then  discarded  for  the  hydrogen  eudi- 
ometer of  Volta.  Subsequently,  Berger^  in  Geneva  laid  especial  em- 
phasis upon  the  errors  of  the  nitric-oxide  method  and  opposed  von  Hum- 
boldt's belief  that  the  nitric-oxide  solution  in  ferrous  sulphate  was  a 
suitable  reagent  for  accurate  oxygen  determinations,  concluding  that  the 
phosphorus  eudiometer  was  very  much  superior. 

Although  the  original  nitric-oxide  method  of  determining  oxygen  was 
destined  to  be  relegated  to  the  ranks  of  impracticable  chemical  operations, 
the  experience  with  it  naturally  led  to  the  employment  by  Davy^  of  a 
solution  of  nitric  oxide  in  ferrous  sulphate.  This  means  of  testing  the 
purity  of  the  nitric  oxide  had  been  advocated  by  von  Humboldt,  and 
Davy  first  made  use  of  the  oxygen-absorbing  power  of  such  a  solution  to 
analyze  air.  Davy  strongly  criticized  the  old  Fontana  nitric-oxide  eudiom- 
eter, but  pointed  out  that  1  c.c.  of  a  reasonably  strong  solution  of  ferrous 


^  von  Humboldt,  Gilbert's  Annalen  der  Physik,  1800, 4,  p.  443. 

'  Seguin,  Annales  de  Chimie,  1791, 9,  p.  293. 

»  von  Humboldt,  Annales  de  Chimie,  1799, 28,  p.  123. 

*  von  Humboldt  and  Gay-Lussac,  Journal  de  Physique,  1805,  60,  p.  129. 
^  Berger,  Journal  de  Physique,  1802,  56,  p.  253. 

•  Davy,  Journal  of  the  Royal  Institution,  1802,  1,  p.  45. 


History  of  Air-Analysis  16 

sulphate  saturated  with  nitric  oxide  would  absorb  5  to  6  c.c.  of  oxygen. 
Comparative  tests  were  made  with  phosphorus  and  alkaline  sulphides. 

In  his  analyses  of  atmospheric  air  with  a  saturated  solution  of  nitric 
oxide,  he  never  found  a  change  in  the  constituents.  The  air  on  October 
3,  1800,  on  the  sea,  at  the  mouth  of  the  Severn,  with  a  strong  west  wind 
blowing  over  the  Atlantic  Ocean,  contained  21  per  cent  of  oxygen.  Ex- 
actly the  same  amount  was  found  in  air  brought  from  the  coast  of  Guinea 
to  Dr.  Beddoes  by  two  Liverpool  surgeons.  Davy's  ingenious  use  of  the 
ferrous-sulphate  solution  of  nitric  oxide  was  short-lived,  for  he  himself 
found  that  the  alkaline  sulphides  always  gave  a  somewhat  larger  absorp- 
tion. 

Allen  and  Pepys^  employed  the  ferrous  sulphate-nitric  oxide  method 
to  analyze  not  only  air,  but  some  gaseous  mixtures  rich  in  oxygen.  They 
report  that  outdoor  air  was  continuously  found  to  contain  21  per  cent  of 
oxygen. 

The  last  writer  to  make  any  considerable  use  of  the  nitric-oxide  eudiom- 
eter was  Dalton,2  who,  comparing  the  Volta  hydrogen  eudiometer  with 
the  nitric-oxide  eudiometer  and  the  sulphide  of  lime  absorption  method, 
says: 

The  nitrous  gas  eudiometer  is  of  singular  utility  on  many  occasions.  No  other  can 
exceed  it  in  accuracy  when  mixtures  contain  very  little,  as  one  or  two  per  cent  of  oxygen; 
or  on  the  other  hand  when  nearly  the  whole  of  the  gas  is  oxygen.  But  when  the  mixture 
of  gases  contains  from  twenty  to  eighty  per  cent  of  oxygen,  as  in  the  case  of  common  air, 
it  is  not  the  best  when  great  exactness  is  required. 

THE  BEGINNINGS  OF  ACCURATE  AIR-ANALYSIS. 

The  early  historical  interest  attaching  to  the  development  and  exten- 
sive use  of  the  nitric-oxide  eudiometer  justifies  the  special  treatment 
which  has  been  given  of  this  method;  nevertheless  other  absorbents  for 
oxygen  were  used.  The  large  number  of  scientists  experimenting  daily 
with  the  newly  discovered  gas,  oxygen,  and  acquiring  information  with 
regard  to  its  properties,  rapidly  brought  together  a  series  of  methods  for 
determining  this  gas  in  air.  While  the  nitric-oxide  method  has  long  been 
discarded  as  utterly  worthless,  the  alkaline  sulphides  first  employed  by 
Scheele  were  for  some  time  used  in  air-analyses,  and  phosphorus  for  absorb- 
ing oxygen,  likewise  employed  by  Scheele,  has  even  to-day  an  extensive 
use.  The  explosion  of  air  with  hydrogen,  first  employed  by  Volta,  has  also 
withstood  the  critical  attacks  of  over  100  years  and  to-day  is  much  used. 

As  Scheele  found  from  his  experiments  with  different  absorptive  agents 
variations  in  the  oxygen  content  of  air,  so  Lavoisier  likewise,  using  various 
agents,  was  unable  to  find  any  satisfactory  value  for  the  percentage  of 
oxygen,  for  we  find  in  his  reports  varying  values  assigned  to  the  oxygen 

*  Pepys,  Philosophical  Transactions,  1807,  Part  I,  p.  247;  Allen  and  Pepys,  Philo- 
sophical Transactions,  1808,  8,  p.  255. 

« Dalton,  Philosophical  Magazine,  1838,  3d  ser.,  12,  p.  158. 


16  Composition  of  the  Atmosphere 

content  of  air.  Lavoisier  was  infinitely  more  interested  in  chemical  prob- 
lems involving  combustion  in  the  air  than  he  was  in  the  exact  composition 
of  air  itself,  and  hence  we  find  his  records  of  air  composition  always  inci- 
dental to  other  important  data. 

Thus,  in  studying  the  properties  of  phosphorus,  ^  he  reports  that  in  a 
large  number  of  experiments  in  which  an  excess  of  phosphorus  was  burned 
in  a  bell  jar  containing  109  pouces^  he  found  a  diminution  in  volume  of  20 
to  21  pouces,  that  is,  about  one-fifth.  Lavoisier  also  noted  an  increase  in 
the  weight  of  the  phosphorus.  Of  particular  interest  is  the  experiment 
reported  in  his  memoir  on  the  respiration  of  animals,^  in  which  he  heated 
mercury  with  a  confined  volume  of  oxygen.  On  heating  50  pouces  of 
common  air  with  4  ounces  of  mercury,  he  found  at  the  end  of  12  days  that 
the  air  was  diminished  one-sixth  part.  In  the  same  year,  1777,  in  his  re- 
port of  the  research  on  the  combustion  of  a  candle,*  he  states  that  the  air 
contains  about  one-fourth  of  its  volume  of  ''air  pur  et  respirable."  Fi- 
nally, in  1785,  in  a  report  of  a  study  of  the  alteration  of  air  by  respir^ation,'^ 
he  maintained  that  air  contains  25  per  cent  of  oxygen. 

Lavoisier's  experience  with  all  known  methods  for  absorbing  oxygen 
justified  his  critical  discussion  of  the  subject^  in  which  he  maintains  that 
the  eudiometers  established  on  the  principle  which  depends  upon  the 
great  affinity  between  oxygen  and  phosphorus,  or  the  alkaline  sulphides, 
or  the  mixture  of  iron  and  sulphur,  are  much  preferable  to  those  of  Priest- 
ley, Font  ana,  and  Ingen-housz  using  nitric  oxide.  In  the  first  place, 
it  is  always  easy  to  have  phosphorus,  sulphur,  and  iron  perfectly  identi- 
cal, while  nitric  oxide  always  differs  in  composition.  Second,  the  nitric 
oxide  does  not  always  absorb  all  of  the  vital  air.  Third,  this  gas  is  sus- 
ceptible of  different  degrees  of  oxygenation  varying  with  the  temperature 
and  pressure,  the  rapidity  of  mixture,  and  the  diameter  of  the  vessel. 
Fourth,  the  nitric  oxide  is  capable  of  mixing  with  nitrogen  in  all  propor- 
tions. An  excess  of  sulphuret  of  potash,  iron,  sulphur,  or  phosphorus 
may  be  used  without  affecting  the  results,  but  with  nitric  oxide  an  excess 
produces  an  error.  Lavoisier  finally  decided  to  use  sulphuret  of  potash, 
preparing  the  air  sample  over  water  and  at  the  end  of  15  to  20  days  de- 
termining the  contraction  in  volume.  The  importance  of  a  general  study 
of  the  oxygen  content  of  the  air  on  the  earth  is  emphasized  in  the  following 
paragraph  from  Lavoisier: 

II  est  k  d6sirer  que  quelque  physicien  ait  le  courage  d'entreprendre,  par  cette  m6thode, 
une  suite  d'exp6riences  sur  I'air  atmosph^rique  recueilli  dans  diff^rents  lieux,  dans  dif- 


I  Lavoisier,  Opuscules  Physiques  et  Chimiques,  1773:  Oeuvres  de  Lavoisier,  1,  p.  643. 
'  A  cubic  pouce  equals  19.6  c.c. 

« Lavoisier,  Memoires  de  1' Academic  des  Sciences,  1777,  p.  185:  Oeuvres  de  Lavoisier, 
2,  p.  174. 

Lavoisier,  Memoires  de  I'Academie  des  Sciences,  1777,  p.  195;  Oeuvres  de  Lavoisier 
2,  p.  184. 

I  Lavoisier,  Recueil  d.  Memoires  de  Lavoisier,  3,  p.  13;  Oeuvres  de  Lavoisier,  2,  p.  676. 
lAvoisier,  Recueil  d.  Memoires  de  Lavoisier,  3,  p.  154;  Oeuvres  de  Lavoisier,  2,  p. 
715. 


History  of  Air-Analysis  17 

f^rentes  saisons,  dans  diff^rentes  circonstances.  On  pourrait  faire  marcher  ensemble 
des  experiences  correspondates  par  la  combustion  du  phosphore.  J'ai  toujours  eu  le 
projet  de  me  livrer  k  ces  recherches,  auxquelles  j'6tais  naturellement  conduit  par  les  ex- 
periences que  j'ai  faites  sur  la  salubrity  de  I'air  des  salles  de  spectacle  et  des  dortoires  des 
h6pitaux;  mais  je  n'ai  pu  encore  r^aliser  mon  projet. 

While  Scheele  first  attempted  a  study  of  the  effect  of  season  and 
weather  conditions  on  the  oxygen  content,  we  find  Lavoisier  empha- 
sizing the  importance  of  recognizing  the  influence  of  geographical  locality 
upon  the  composition  of  the  atmosphere. 

Alkaline  sulphides  were  used  by  Guyton^  to  absorb  the  oxygen  quan- 
titatively from  the  air;  calcium  sulphide  was  likewise  employed  by  de 
Marti^  in  his  analyses  of  the  air  of  Catalonia.  Upon  comparing  the  dif- 
ferent methods — nitric  oxide,  the  Volta  hydrogen  eudiometer,  phosphorus, 
moist  iron  and  sulphur,  and  the  alkaline  sulphides — de  Marti  decided 
the  last  was  the  most  satisfactory.  The  experiments  were  made  during 
1787,  and  his  results  are  of  especial  interest,  as  they  show  his  remarkable 
intuitiveness. 

Among  other  refinements,  de  Marti  recognized  the  importance  of  sat- 
urating his  absorbing  solution  with  nitrogen  before  use.  He  says  regard- 
ing his  researches : 

The  proof  by  sulphuret  is  that  best  calculated  to  ascertain  the  quantity  of  vital  air 
contained  in  any  gaseous  fluid,  since  it  will  leave  the  mephitic  air,  and  the  other  kinds  of 
air  which  do  not  combine  with  it,  without  fear  of  any  other  gaseous  substance  being  pro- 
duced, or  any  lost,  except  the  quantity  of  vital  air,  which  alone  has  an  affinity  with  the  sul- 
phuret, as  I  assured  myself  in  1787.  A  hundred  parts  of  atmospheric  air  exposed  to  sul- 
phuret lost  between  0.21  and  0.23;  and  as  several  other  proofs  on  the  same  air,  made  with 
nitrous  gas,  had  taught  me  that  it  experienced  no  sensible  variation,  I  was  then  convinced 
that  the  air  which  we  breathe  in  Catalonia  is  constantly  composed  of  from  0.21  to  0.23  of 
vital  air,  and  from  0.77  to  0.79  of  azotic  gas.  To  ascertain  whether  there  might  not  be 
variations  afterwards  in  the  proportion  of  these  two  principles  which  constitute  in  the 
atmosphere  that  elastic  substance  on  which  oiu*  life  chiefly  depends,  I  continued  my 
experiments  by  means  of  sulphuret. 

I  repeated  them  so  many  times  with  atmospheric  air,  and  on  so  great  a  number  of 
days,  that  the  uniformity  in  my  results  demonstrates  not  only  the  exactness  of  this 
method,  but  it  seems  to  result  from  my  observations  made  on  the  southern  coast  of 
this  province: 

1st,  That  the  wind  never  caused  the  variation  of  a  hundredth  part  in  the  respective 
quantities  of  vital  air  and  azotic  gas  which  compose  the  elastic  fluid  of  our  atmosphere, 
since  I  have  always  found  that  a  hundred  parts  contained  79  of  the  latter  and  21  of  the 
former,  without  ever  reaching  22. 

2nd,  That  neither  the  moisture  nor  dryness  of  the  atmosphere,  nor  the  state  of  the 
latter  in  being  more  or  less  charged  with  exhalations,  nor  serene  nor  rainy  weather,  oc- 
casioned any  difference. 

3d,  That  the  proportion  of  the  quantities  of  the  two  same  principles  was  equally 
constant  during  the  days  that  Reaumur's  thermometer  stood  at  the^freezing  point,  as 
well  as  during  those  when  it  indicated  24  degrees  of  heat. 

»  Guyton,  Chemisches  Annalen,  1788,  I,  p.  316;  ibid,  1796,  I,  p.  22. 
'  de  Marti,  Journal  de  Physique,  1801,  52,  p.  173;  also  printed  in  Philosophical  Maga- 
zine, 1801, 9,  p.  250. 


13  Composition  of  the  Atmosphere 

4th,  That  I  did  not  observe  any  variation  in  the  air  thus  taken  while  the  mercury  of 
the  barometer  was  very  low,  and  when  it  exceeded  28  inches. 

In  a  word,  during  winter,  in  summer,  in  spring,  and  in  autumn,  m  every  month  and 
at  all  hours,  I  found  the  air  of  my  country,  taken  in  the  open  fields,  to  be  always  composed 
of  from  21to  22  parts  of  vital  air,  and  of  from  78  to  79  of  azotic  gas. 

But  though  this  proportion  does  not  vary  a  hundredth  part  in  the  course  of  several 
months,  and  even  years,  may  it  vary  a  very  small  part,  such  as  a  thousandth  part,  which 
after  a  very  long  time  may  become  sufficiently  sensible  to  make  the  proportion  of  the 
vital  air  of  the  atmosphere  experience  a  progressive  or  periodical  increase  or  diminution? 

De  Marti's  researches,  though  carried  out  in  1787,  were  not  translated 
into  English  until  1801,  but  his  success  with  the  sulphide  of  calcium  evi- 
dently stimulated  others  to  use  the  sulphides  as  reagents. 

Berger^  reports  a  series  of  experiments,  using  several  forms  of  sul- 
phide. With  potassium  sulphide,  he  found  21.65  per  cent  of  oxygen; 
with  iron  sulphide,  21.19  per  cent;  with  calcium  sulphide,  20.88  per  cent; 
and  with  sodium  sulphide,  20.38  per  cent.  The  agreement  in  these  deter- 
minations led  Berger  to  conclude  that  these  eudiometric  substances  ab- 
sorb from  the  air  only  one  substance,  namely,  oxygen. 

Henderson, 2  studying  the  changes  which  air  undergoes  as  a  reslilt  of 
respiratory  processes,  used  ^'sulphuret  of  Hme."  On  three  days,  June  16, 
1803,  June  18,  1803,  and  February  11,  1804,  he  analyzed  common  air  and 
found  22  per  cent  of  oxygen  in  all  three  cases. 

Gay-Lussac,'  using  both  the  hydrogen  eudiometer  and  the  absorp- 
tion by  alkaline  sulphides,  made  analyses  of  air  collected  in  a  balloon. 
He  found  with  the  hydrogen-explosion  method  that  the  air  at  a  height  of 
6636  meters  had  the  same  composition  as  that  on  the  surface  of  the  earth, 
and  that  at  both  places  they  gave  21.49  per  cent  of  oxygen.  With  the 
alkaline  sulphide  solution,  he  found  21.63  per  cent  in  the  air  brought  down 
in  the  balloon,  and  maintained  that  this  slight  increase  over  21.49  per  cent 
was  inside  the  limit  of  error  of  the  apparatus. 

Julia  de  Fontanelle,^  while  making  a  tour  of  Europe,  analyzed  over  50 
samples  of  air  in  France  at  the  foot  and  summit  of  Canigou,  with  an  ele- 
vation of  2780  meters,  on  the  Corbi^res,  on  the  Clape,  and  on  the  plains 
of  Roussillon  and  Narbonne;  also  in  Spain  on  the  plains  of  Figueras, 
Gironne,  and  Barcelona,  and  on  the  mountains  of  St.  Jerome-D'  Ebron, 
Mont-Joui,  etc.  Using  calcium  sulphide,  he  found  constantly  21  per 
cent  of  oxygen,  with  shghtly  more  oxygen  at  noon  than  at  midnight. 

The  last  recorded  use  of  the  sulphide  of  calcium  for  air-analysis  was 
made  by  Dalton,^  who,  however,  gives  no  results,  and  by  Moyle,^  who 
analyzed  the  air  of  mines  by  this  method  in  comparison  with  several 
others,  including  the  long-discarded  nitric-oxide  method. 

» Berger,  Journal  de  Physique,  1802, 56,  p.  375. 

•  Henderson,  Nicholson's  Journal,  1804, 8,  p.  40. 
»  Gay-Lussac,  Annales  de  Chimie,  1804,  52,  p.  75. 

•  J.-S.-E.-JuUa,  Recherches  historiques,  chimiques  et  m6dicales  sur  I'air  mar6- 
cageaux.  Paris,  1823. 

» Dalton,  Philosophical  Magazine,  1838, 3d  ser.,  12,  p.  158. 

•  Moyle,  Annales  de  Chimie  et  de  Physique,  1841, 3d  ser.,  3,  p.  318. 


History  of  Air-Analysis  -     19 

With  the  passing  of  the  nitric-oxide^  and  the  alkaUne-sulphide  methods, 
we  may  consider  the  historical  development  of  such  methods  as  have  sur- 
vived a  century  or  more  of  keen  analytical  criticism.  Since  this  article 
has  to  deal  primarily  with  the  development  of  the  knowledge  regarding 
the  composition  of  the  outdoor  air  and  but  secondarily  with  methods,  we 
may  now  advantageously  consider  the  chronological  records  of  progress 
in  air-analysis. 

In  1774,  the  briUiant  ItaHan  physicist,  Volta,^  announced  his  eudio- 
metric  method  of  employing  the  explosion  of  a  confined  volume  of  air 
with  hydrogen  by  the  electric  spark.  No  results  of  his  analyses  are  re- 
ported, but  the  process  evidently  attracted  much  attention,  for  we  find 
that  Cavendish,^  while  working  on  the  composition  of  water,  published 
the  following  interesting  statements: 

From  the  fourth  experiment  it  appears  that  423  measures  of  inflammable  air  are 
nearly  sufficient  to  completely  phlogisticate  1000  of  common  air;  and  that  the  bulk  of 
the  air  remaining  after  the  explosion  is  then  very  little  more  than  four-fifths  of  the  com- 
mon air  employed;  so  that  as  common  air  can  not  be  reduced  to  a  much  less  bulk  than 
that  by  any  method  of  phlogistication,  we  may  safely  conclude,  that  when  they  are  mixed 
in  this  proportion,-  and  exploded,  almost  all  the  inflammable  air,  and  about  one-fifth  part 
of  the  conamon  air,  lose  their  elasticity,  and  are  condensed  into  the  dew  which  lines  the 
glass. 

Although  Cavendish  was  in  no  sense  appreciative  of  the  fact  that  this 
series  of  experiments  proved  the  accuracy  of  the  Volta  eudiometer  for  air- 
analysis,  the  results  are  surprisingly  accurate. 

Shortly  afterwards  the  method  was  adversely  criticized  by  Seguin,* 
who  maintained  that  the  apparatus  gave  only  comparative  results  and 
could  never  be  taken  as  an  absolute  measure,  and  by  Berthollet,^  who  ob- 
jected to  the  complicated  apparatus.  The  latter  remarked  on  the  prob- 
able contamination  of  the  hydrogen  by  carbonaceous  gases  and  pointed 
out  that  we  do  not  as  yet  know  enough  about  the  specific  weight  of  the 
two  different  gases.  But  in  spite  of  this  adverse  criticism,  the  method 
was  most  carefully  employed  in  analyzing  samples  of  air  brought  from  a 
great  height  by  Gay-Lussac  in  a  balloon  flight.^  Later,  von  Humboldt 
and  Gay-Lussac^  published  a  long  research  with  the  Volta  eudiometer 
on  the  composition  of  air  taken  over  the  Seine  under  varying  weather 

1  It  is  interesting  to  note  that  in  1890  Wanklvn  and  Cooper  resurrected  the  nitric- 
oxide  method  and  enthusiastically  recommended  its  use,  reporting  three  analyses  of 
pure  air  as  giving  20.59,  20.54,  and  20.67  per  cent  of  oxygen  respectively.  Chemists 
have  not  accepted  the  method  for  modem  use.  (See  Wankl}^!  and  Cooper,  Air-analysis, 
London,  1890,  p.  35.) 

'  Volta,  Sopra  Un  Nova  Eudiometro.  Lettera  al  Signor  Dottore  Giuseppe  Priestley, 
Como,  2  Settembre,  1777.  Published  in  Collezione  dell'Opere.  del  Cavaliere  Conte 
Alessandro  Volta,  Firenze,  1816,  3,  p.  177.  Originally  published,  Scelta  di  Opuscoli 
interessanti  di  Milano,  1777,  34,  p.  65. 

3  Cavendish,  Philosophical  Transactions,  1784,  74,  pp.  119-153. 

*  Seguin,  Annales  de  Chimie,  1791, 9,  p.  293. 

'  Berthollet,  Memoires  sur  I'Egypt  publi6s  pendant  les  Campagnes  du  G^n^ral  Bona- 
parte.   Paris,  1800  ( Ann6e  8) ,  p.  284. 

*  Gay-Lussac,  Annales  de  Chimie,  1805,  52,  p.  75. 

'  V.  Humboldt  and  Gay-Lussac,  Journal  de  Physique,  60,  p.  129. 


20 


Composition  of  the  Atmosphere 


conditions.  Although  in  the  analyses  of  air  collected  by  Gay-Lussac  in 
the  balloon,  the  ratio  of  hydrogen  to  oxygen  was  erroneously  taken  as 
2  04  to  1,  von  Humboldt  and  Gay-Lussac  used  in  this  research  the  correct 
ratio,  2  to  1,  which  had  but  recently  been  established.  In  this  paper  von 
Humboldt  acknowledges  his  error  in  advocating  so  strongly  the  nitric- 
oxide  eudiometer  in  his  contention  with  Berthollet  a  few  years  before. 

The  analyses  of  the  air  were  made  on  the  day  of  collection,  a  sum- 
mary of  the  results  being  given. 

Table  \— Results  of  a  research  on  the  composition  of  air,  made  mith  the  VoUa  eudiometer, 
by  Humboldt  and  Gay-Lu^sac. 


Date. 


ISOt 
Nov.    17 

Nov.  18 

Nov.  19 

Nov.  20 

Nov.  21 

Nov.  22 

Nov.  23 

Nov.  24 

Nov.  25 

Nov.  26 

Nov.  27 

Nov.  28 

Dec.  1 

Dec.  3 

Dec.  5 

Dec.  7 

Dec.  13 

Dec.  19 

Dec.  23 


Temper- 
ature. 


°C. 

7.3 

4.5 

4.7 

10.0 

12.5 

6.7 

1.5 

8.5 

10.6 

3.3 

1.6 
1.3 
4.1 
2.3 
4.2 
3.1 
9.6 
2.2 
1.0 


Weather  conditions. 


Overcast    

....Do 

Fine  rain 

....Do 

Overcast    

Cloudy;  little  rain 

Cloudy 

Rain     

Overcast    

Cloudy 


Wind. 


Frost    

Snow    

Fog 

Cloudy 

Rain     

Thick  Fog 

Rain     

Overcast    

Heavy  frost;  thick  fog. 


E 

ESE 

Very  strong,  SW.  to  W. 

S :... 

SW 

SW 

W 

S 

SW 

E 


N.  . 
N.  . 
NNE. 
E.... 
S.    .. 


SSW. 
NE. 
SE.  . 


Oxygen. 


p.  ct. 

21.0 
21.0 
21.0 
21.0 
21,0 
21X) 
21.0 
21.1 
21.2 
21.0 
21.0 
21.0 
21.0 
21.0 
21.0 
21.1 
21.0 
21.1 
21.1 
21.0 
21.1 
21.0 
21.0 
20.9 
21.0 
21.0 
21.0 
21.0 
21.0 


The  authors  conclude  that  they  have  shown,  first,  that  the  atmos- 
pheric air  does  not  vary  in  composition;  second,  that  there  are  21  parts  of 
oxygen  in  100  parts  of  air;  third,  that  there  are  no  noticeable  amounts  of 
hydrogen  present  in  the  air.  This  investigation  is  the  first  extensive  re- 
search into  the  composition  of  the  atmosphere  employing  the  hydrogen 
eudiometer,  and  the  conclusions  drawn  by  the  authors  are  astonishingly 
correct  when  it  is  considered  that  the  research  was  carried  out  over  a  cen- 
tury ago.  That  the  errors  in  the  apparatus  were  far  greater  than  are 
permissible  in  modern  research,  especially  when  such  fundamental  de- 
du(;tions  are  to  be  made,  should  not  in  any  way  dim  the  brilliancy  of  the 
work  of  these  investigators.    Subsequently,  the  method  was  to  have  exten- 


History  of  Air-Analysis  21 

sive  use,  be  considerably  increased  in  accuracy,  and  contribute  materially 
to  our  knowledge  of  the  oxygen  content  of  the  air. 

Henry^  analyzed  atmospheric  air  frequently,  using  the  Volta  eudiom- 
eter. He  reports  that  he  was  unable  to  satisfy  himself  "whether  it  con- 
tains 21  or  20  volumes  of  oxygen  in  100,  the  proportion  being  mostly  be- 
tween these  two  extremes." 

Simultaneously  with  the  Volta  eudiometer,  another  method  of  air- 
analysis  was  rapidly  developed,  which  was  also  based  upon  the  fundamen- 
tal observations  of  Scheele  with  regard  to  the  absorption  of  oxygen  from 
a  confined  volume  of  air  by  slowly  or  rapidly  burning  phosphorus. 
Scheele's  experiments  have  already  been  cited,  but  in  the  English  trans- 
lation of  his  book,2  ^q  gj^^j  Richard  Kirwan  criticizing  adversely  Scheele's 
results,  maintaining  that  Lavoisier,  when  using  the  combustion  of  phos- 
phorus, never  found  more  than  between  one-fifth  and  one-sixth  of  oxygen 
absorbed,  while  Scheele,  it  will  be  remembered,  found  a  much  larger 
contraction  in  volume.  Kirwan  also  pointed  out  that  Fontana  had  made 
experiments  with  phosphorus  but  found  the  diminution  in  volume  much 
less  th  an  that  found  by  Scheele.  Later  Lavoisier ^  mentioned  the  fact  that 
when  employing  the  combustion  of  phosphorus  he  found  the  quantity  of 
vital  air  contained  in  the  atmosphere  was  about  27.5  parts  in  100. 

Volta,  in  a  letter  to  Priestley,^  wrote  in  a  general  way  of  his  experience 
with  "Bolognian  phosphorus,"  showing  that  at  the  same  time  Scheele  in 
Sweden,  Lavoisier  in  Paris,  and  Volta  in  Italy  were  using  phosphorus  to 
absorb  oxygen  from  the  air.  Rapidly  burning  phosphorus  was  also  em- 
ployed by  Achard,^  who  described  two  eudiometers,  one  for  nitric  oxide 
and  one  for  rapidly  burning  phosphorus. 

Dissatisfied  with  the  incomplete  descriptions  and  development  of  the 
earlier  methods  employing  ignited  phosphorus,  Seguin^  in  his  memoir  on 
eudiometry  described  accurately  the  methods  used  by  Lavoisier  and  him- 
self, but  gave  no  results.  It  is  noteworthy  that  after  the  ignition  of  the 
phosphorus  and  the  contraction  in  the  volume  of  the  air,  they  placed  in  the 
jar  a  little  caustic  alkali  to  absorb  the  carbon  dioxide  and  the  phosphoric 
acid.    Seguin  maintained  that  this  method  was  very  rapid  and  very  exact. 

Simultaneously  with  his  condemnation  of  the  nitric-oxide  eudiometer, 
Berthollet  advocated  the  use  of  slow-burning  phosphorus.^  In  his  ob- 
servations on  eudiometry,  he  criticized  severely  the  nitric-oxide  eudiometer 
and  the  Volta  hydrogen  eudiometer,  and  stated  that  the  use  of  alkaUne 
sulphide  is  too  long  a  process  and  that  hydrogen  sulphide  is  present. 

1  Henry,  Elements  of  experimental  chemistry,  London,  1829, 11th  ed.,  1,  p.  316. 

'  Scheele,  Experiments  on  air  and  fire,  London,  1780,  p.  202. 

'  Lavoisier,  Memoires  de  I'Academie  des  Sciences,  1782,  p.  486;  also  in  Oeuvres  de 
Lavoisier,  1862,  2,  p.  503. 

*  Priestley,  loc.  cit.,  1777,  3,  p.  381. 

^  Achard,  Nouveaux  Memoire  de  TAcademie  Royale  des  Sciences  et  Belles  Lettres, 
for  the  year  1778  (published  1780),  p.  91. 

«  Seguin,  Annales  de  Chimie,  1791,  9,  p.  293. 

^  Berthollet,  Memoires  sur  I'Egypt  publics  pendant  les  Campagnes  du  G^n^ral  Bona- 
parte.   Paris,  1800,  (Ann6e  8),  p.  284. 


22  Composition  of  the  Atmosphere 

Berthollet's  expressions  regarding  the  existing  condition  of  air-analysis 
methods  is  of  special  interest  even  at  the  present  day: 

Depuis  que  I'on  sait  que  I'air  atmosph^rique  est  compost  de  gaz  oxyg^ne  et  de  gaz 
azote,  on  a  cherch^  k  determiner  les  proportions  de  ces  deux  gaz,  et  les  variations  que 
peuvent  y  survenir;  mais  on  n'est  point  encore  d'accord  sur  la  m^thode  qu'on  doit 
pr6f 6rer,  et  sur  le  r6sultat  auquel  on  doit  s'arreter. 

Believing  the  use  of  slow-burning  phosphorus  to  be  the  best  method, 
he  passed  a  cylindrical  stick  of  phosphorus  into  air  collected  over  water  in 
a  glass  vessel.  At  the  ordinary  temperature  of  Cairo  it  required  about  2 
hours  for  complete  absorption,  but  in  Paris  he  found  it  required  6  to  8 
hours.  A  correction  of  one-fortieth  for  phosphorus  vapor  was  recom- 
mended. In  Cairo  he  found  that  the  air  contained  generally  22  parts  of 
oxygen,  with  a  variation  of  hardly  more  than  0.5  part.  A  most  interest- 
ing discussion  of  the  factors  affecting  the  composition  of  the  atmosphere 
concludes  his  paper: 

En  efifet,  comment  peut-on  concevoir  que  Tatmosphere  continuellement  agit^e  par 
des  mouvements  qui  la  transportent  rapidement,  qui  changent  ses  contacts  et  la  renou- 
vellent,  puisse  varier  consid^rablement  d'un  village  a  un  autre:  il  y  a  cependant  una 
exception  k  faire  pour  les  lieux  qui  sont  fort  61ev6s  audessus  du  niveau  de  la  mer.  La 
diflf^rence  de  pesanteur  sp^cifique  entre  le  gaz  oxyg^ne  et  le  gaz  azote,  qui,  dans  I'etat 
eiastique,  n'exercent  r^ciproquement  qu'une  tr^s  faible  action,  explique  celle  qui  a  6t6 
trouv^e  dans  leurs  proportions. 

Parrot  in  Riga  began  active  experimenting  in  phosphorus  eudiometry 
in  the  latter  part  of  1799,  and  in  1800  described  an  apparatus  which  he 
called  an  oxygenometer.^  In  a  letter  to  Gilbert^  he  emphasized  the  im- 
portance of  temperature  changes,  noting  that  a  change  of  4°  or  5°  Reau- 
mur may  produce  a  change  of  1  to  2  per  cent  in  the  oxygen  measurement. 
In  his  later  experiments  he  found  that  the  oxygen  varied  from  20.7  to  23 
per  cent.  By  applying  a  correction — not  identical,  however,  with  Berth- 
ollet's one-fortieth — the  results  were  22.25  and  24.72  per  cent  by  volume. 
He  concluded  that  the  greatest  variation  was  2.5  per  cent  and  that  the 
greatest  oxygen  content  of  the  air  was  about  25  per  cent.  His  argu- 
ments for  variation  in  the  oxygen  content  of  the  atmosphere  are  of  interest : 

Der  Grund,  den  Berthollet  fur  die  Bestandigkeit  des  Sauerstoffgehalts  angiebt,  nam- 
lich  die  Bewegung  der  Luft,  beweist  allerdings,  dass  dieser  Gehalt  nicht  sehr  stark 
variieren  kann,  schliest  aber  Variationen  von  2  bis  2i  pC.  nicht  aus,  es  versteht  sich,  fiir 
sehr  entfemte  Orte  und  verschiedne  Zeiten.  Ein  Wind,  der  15  Fuss  in  einer  Sekunde 
durchlauft,  braucht  etwa  5  Tage,  um  eine  Strecke  von  18°  zu  durchstreichen.  Warum 
sollte  z.  B.  vor  einem  Siidwinde  die  Luft  in  Schottland,  Schweden,  Norwegen,  Russland 
nicht  an  Sauerstoff  armer  seyn,  als  5  Tage  nach  dessen  Entstehung,  wenn  z.  B.  eine 
iippige  Vegetation,  von  vielem  Sonnenscheine  begunstigt,  viel  Sauerstoffgas  in  Italien, 
im  nordlichen  Afrika,  in  Griechenland  entwickelt  hat  ?  Warum  sollte  ein  Ostwind,  der 
Gber  Asiens  Vegetation  herkommt,  nicht  Europa  mit  mehr  Sauerstoff  versehen,  als  der 
Westwind,  der  ttber  das  atlantische  Meer  herweht,  wo  er  keine  Sauerstoff-Entwickelung 
antrifft? 

» Parrot,  Voigt's  Magazine,  1800, 2,  p.  154. 

« Parrot,  Gilbert's  Annalen  der  Physik,1802, 10,  p.  193. 


History  of  Air-Analysis 


23 


F.  Berger^  in  Geneva,  in  a  paper  criticizing  the  Fontana  eudiometer, 
mentions  the  phosphorus  eudiometer  as  ''introduced"  by  Giobert^  of 
Turin  and  "improved"  by  Spallanzani.^  A  number  of  tests  comparing 
the  nitric-oxide  with  the  phosphorus  eudiometer  all  show  the  great  advan- 
tage of  the  latter.  Using  both  alkaline  sulphides  and  the  phosphorus 
eudiometer,  he  always  found  between  20  and  21  per  cent.  He  analyzed 
air  from  the  glacier  of  Mont  Cervin  and  other  glaciers,  but  found  the  air 
over  the  glacier  no  purer  than  air  from  the  same  height  on  a  mountain. 
He  concludes  that  the  atmosphere  is  throughout  the  whole  extent  of  equal 
composition  and  that  the  oxygen  is  very  nearly  one-fifth  of  the  total  air. 

The  activity  of  numerous  chemists  in  advocating  various  methods  for 
absorbing  oxygen  led  to  the  rapid  accumulation  of  evidence  in  favor  of 
the  phosphorus  and  hydrogen  eudiometers,  but  the  latter  seemed  to  have 
the  most  extended  use. 

Biot,*  during  a  study  of  the  air  contained  in  the  bladders  of  fishes, 
analyzed  the  air  of  two  islands  in  the  Mediterranean,  Formentera  and 
Iviza.  They  report  that  the  analyses,  which  were  made  by  the  hydrogen- 
explosion  method,  showed  consistently  an  oxygen  content  of  21  per  cent. 

In  a  like  research,  i.e.,  the  analysis  of  the  air  contained  in  the  bladders 
of  fishes,  ConfigUachi^  used  side  by  side  the  phosphorus  and  the  hydrogen 
eudiometers,  but  apparently  was  more  confident  of  results  obtained  with 
the  latter.  In  this  research,  analyses  were  made  of  outdoor  air  from  moun- 
tains, marshes,  and  grain  fields.  He  concludes  that  his  results,  which 
are  given  in  table  2,  show  the  uniform  composition  of  the  atmosphere. 

Table  2. — Comparative  study  of  the  percentage  of  oxygen  in  atmospheric  air, 
made  by  Configliachi. 


Air  of  lowlands. 

Mountain  air. 

Grain 
field. 

Marsh. 

Pizzo  Legnone  (2642  meters) . . . 
St.  Bernard  (472  meters) 

Mont  Cenis  (2067  meters) 

Simplon  (2006  meters) 

iifo 

21.1 

21.0 
20.9 

26!9 

^20.8 
{20.8 
^20.7 
{20.6 
20.8 

p.ct. 
21.0 
20.9 
21.0 
21.0 
20.9 
21.9 

Employing  a  phosphorus  eudiometer,  Vogel^  found  in  the  air  from  the 
Baltic  Sea  between  20  and  21  per  cent  of  oxygen,  the  latter  figure  never 


*  Berger,  Journal  de  Physique,  1802,  56,  p.  253. 

*  Giobert  (Journal  de  Physique,  1798,  47,  p.  197)  analyzed  the  air  of  Vaudier  and  of 
Turin  by  the  combustion  of  phosphorus.  This  refers  probably  to  rapid  rather  than 
slow  combustion.  In  Vaudier  he  found  from  25  to  33  per  cent  of  oxygen,  but  in  Turin  the 
variation  was  much  less,  being  26  to  28  per  cent. 

'  Spallanzani,  in  his  Memoires  sur  la  Respiration,  Geneva,  1803,  p.  101,  states  that 
the  air  we  breathe  contains  27  per  cent  of  oxygen. 

*  Biot,  Gilbert's  Annalen  der  Physik,  1807,  26,  p.  459. 

'  Configliachi,  Journal  fiir  Chemie und  Physik,  1811,  I,  p.  137. 

*  Vogel,  Gilbert's  Annalen  der  Physik  und  der  physikaUschen  Chemie,  1820,  6,  p.  93. 


24  Composition  of  the  Atmosphere 

being  attained.  Kruger  reported  to  Vogel  the  result  of  four  analyses,  made 
with  a  Volta  eudiometer,  of  sea-air  taken  on  a  half  mile  from  shore,  in 
which  he  never  found  over  20.59  per  cent  of  oxygen.  The  author's  explana- 
tion of  this  low  figure  is  that  the  oxygen  had  been  absorbed  by  the  water. 

Another  investigation  of  air  from  the  Baltic  Sea  was  made  by  Hermb- 
stadt^  in  1821.  Although  his  method  of  sampling  is  questionable,  he 
asserts  that  he  employed  a  'Very  exact"  Volta  eudiometer.  Air  taken 
5  feet  above  the  surface  of  the  sea  gave  21.5  per  cent  of  oxygen;  air  16  feet 
above  the  sea,  20.5  per  cent;  and  air  24  feet  inland  from  the  shore,  ex- 
actly 20  per  cent.  The  author  concludes  that  the  larger  oxygen  content 
of  air  from  the  sea  is  due  to  the  continuous  evolution  of  oxygen  from  either 
the  sea-water  or  marine  life. 

Thomson,  2  in  Edinburgh,  was  occupied  in  air-analysis  many  years  and, 
indeed,  states  that  in  1801  he  made  experiments  which  showed  that  the 
composition  of  the  air  in  Edinburgh  was  the  same  as  that  found  by  Davy 
and  Berthollet  elsewhere.  In  1824  he  made  a  new  series  of  tests,  employ- 
ing the  Volta  eudiometer.  After  much  experimenting  as  to  the  proper 
volume  of  hydrogen  to  use,  he  found,  as  the  average  of  10  experinients, 
79.9335  per  cent  of  nitrogen  and  20.0665  per  cent  of  oxygen.  Thomson's 
analyses  and  conclusions  are  so  obviously  dominated  by  the  precon- 
ceived notion  that  air  is  a  chemical  compound  consisting  of  four  parts  of 
nitrogen  and  one  of  oxygen,  that  his  contribution  has  very  little  quanti- 
tative interest. 

Another  Englishman,  John  Dalton,  whose  theoretical  discussions  were 
of  great  importance  to  chemists,  also  analyzed  air  upon  a  number  of 
occasions.  On  January  8, 1825,^  he  found  as  a  result  of  many  experiments, 
21.15  per  cent  of  oxygen  in  air  sampled  in  the  country,  the  barometer 
being  30.9  inches,  and  the  wind  blowing  very  moderately  from  the  north- 
east after  3  days  of  calm  and  a  light  frost.  He  states  that  ordinarily  the 
atmosphere  has  only  20.7  to  20.8  per  cent  of  oxygen.  Dalton's  concep- 
tion of  the  independent  nature  of  each  gas  and  the  computed  differences 
in  composition  of  the  air  at  different  heights  greatly  stimulated  research  in 
this  direction.  In  contradiction  of  his  expressed  views  upon  the  solu- 
bility of  gases  in  water,  he  collected  samples  by  letting  the  water  run  out 
of  a  bottle  and  then  corking  the  bottle.  Frequently  it  was  opened  under 
water  and  allowed  to  stand  several  months.  In  the  Philosophical  Maga- 
zine, 1838,  12,  p.  397,  Dalton  gives  further  experimental  evidence  to  sup- 
port his  view,  but  is  evidently  convinced  that  the  theoretical  compu- 
tations are  not  verified  by  experiment.     Thus  he  states : 

From  the  experiments  about  to  be  related,  I  have  reason  to  believe  that  the  higher 
regions  of  the  atmasphere  are  somewhat  less  abundant  in  the  proportion  of  oxygen  than 

»  Hermbstadt,  Journal  ftir  Chemie  und  Physik^  1821,  32,  p.  283. 

» Records  of  general  science,  by  Robert  D.  Thomson,  M.D.,  1836,  15,  p.  179.     See 
also  Journal  fur  praktische  Chemie,  1836,  8,  p.  359. 
'  Dalton,  Annals  of  Philosophy,  1825.  10,  p.  304. 


History  of  Air-Analysis 


25 


the  lower,  though  the  reverse  might  be  expected  from  the  enormous  consumption  of 
oxygen  by  daily  processes  on  the  surface  of  the  earth,  when  we  know  of  no  proportionate 
consumption  of  azote.  It  appears,  however,  that  the  disproportion  of  the  two  elements 
at  different  elevations  is  by  no  means  so  great  as  theory  requires;  and  therefore  we  must 
conclude  the  unceasing  agitation  of  the  atmosphere  by  currents  and  counter-currents  is 
sufficient  to  maintain  an  almost  uniform  mixture  at  the  different  elevations  to  which 
we  have  access. 

His  experimental  evidence  consists  of  analyses  of  samples  from  Mount 
Helvellyn  (3000  feet),  Snowdon  (3570  feet),  two  balloon  journeys  made 
by  Green  at  9600  feet  and  15,000  feet  respectively,  and  three  samples 
from  Switzerland  sent  by  Crewdson  from  Mer  de  Glace,  the  Simplon 
Pass,  and  the  "Wengern  Alps.  The  results,  together  with  an  abstract  of 
the  many  analyses  of  Manchester  air  made  for  comparison,  are  given  in 
table  4. 

Referring  to  the  results  obtained  from  these  analyses,  Dalton  says: 

The  general  conclusions,  it  seems  to  me,  to  be  drawn  from  these  experiments  are,  that 
the  proportion  of  oxygen  to  azote  in  the  atmosphere  on  the  surface  of  the  earth  is  not 
precisely  the  same  at  all  places  and  times;  and  that  in  elevated  regions  the  proportion  of 
oxygen  to  azote  is  somewhat  less  than  at  the  surface  of  the  earth,  but  not  nearly  so  much 
so  as  the  theory  of  mixed  gases  would  require;  and  that  the  reason  for  this  last  must  be 
found  in  the  incessant  agitation  in  the  atmosphere  from  winds  and  other  causes. 

Numerous  computations  as  to  the  composition  of  the  atmosphere  in 
higher  strata,  based  upon  Dalton's  hypotheses,  have  been  made  from  time 
to  time  by  Babinet,^  Benzenberg,^  Bauer,^  Morley,*  and  Hinrichs.^  The 
values  computed  by  Morley  and  Hinrichs  are  given  in  table  3. 


Table  3. — Percentages  of  oxygen  in  high-strata  air,  as  computed  by 
Morley  and  Hinrichs. 


Oxygen. 

Oxygen. 

Height. 

Height. 

j                        1 

Morley. 

Hinrichs. 

Morley. 

Hinrichs. 

kilometers. 

p.ct. 

p.  ct. 

kilometers. 

1 
p.  ct.        1        p.  ct. 

0 

20.96 

21.00 

10 

18.31          18.43 

1 

20.68 

! 

20 

15.92          16.07 

2 

20.41 

30 

13.90 

3 

20.14 

40 

11.86 

4 

19.87 

1 

60 

10.25            9.83 

5 

19.60 

60 

....      1       7.52 

6 

19.34 

70 

4.7 

7 

19.07 

80 

2.2 

8 

18.82 

90 

0.7 

9 

18.56 

100 

4.69 

0.3 

*  Cited  by  Dumas  and  Boussingault,  Annales  de  Chimie  et  Physique,  1841,  3d  ser., 
3,  p.  258. 

'  Benzenberg,  Poggendorff 's  Annalen  der  Physik  und  Chemie,  1834,  3 1 ,  p.  8. 
'Bauer,  Poggendorff's  Annalen  der  Physik  und  Chemie,  1868,   135,  p.  135;  also 
Zeitschrift  fur  analytische  Chemie,  1869,  8,  p.  397. 

*  Morley,  The  American  Journal  of  Science,  1879, 3d  ser.,  18,  p.  168. 
» Hinrichs,  Comptes  rendus,  1900,  131,  p.  442. 


26 


Composition  op  the  Atmosphere 


Table  4. — Percentages  of  oxygen  in  analyses  of  air  made  by  Dalton. 


Date. 


1824 
July   14 

July  14 
Nov.  23 

1825 
Jan.     8 

June    8 
June  10 

Nov.    3 

1826 
May  14^ 


May  14 

May  18« 
May  18* 

May  18 

May  18 
July 

1827 
June  27» 

June  27 
July     2 

1828 
Aug.    5 
Aug.    5 

1831 
July     4t* 

1832 
July  26 


July  27 

1835 
Aug.  21» 
Aug.  21» 
Aug.  29* 
Aug.  29» 
Sept.  15* 
Sept.  15* 


No.  of 

experi- 
ments 
averaged. 


4 
6 

10 

10 


5 
10 


7 
8 

13 
2 


Barom> 
eter. 


28.0 

30.94 

29.90 
30.30 

28.76 

26.20 


16.8 


Weather. 


Rain;    wind  SE., 
strong. 

Following  a  week  of 
calm  weather. 


Sunny  and    sultry: 

wind  SW. 
Rainy;  wind  SW.. .  . 

Wind  NE.,  light 


Wind  SW.,  Ught 


Rain  and  fog;  wind 
SW. 


Place. 


Summit  of  Helvellyn 
(3000  ft.). 

Manchester 

Town  air 


....Do 


...Do 

Field  near  the  town  . 


Town  air. 


Summit  of  Snowdon, 
3570  ft.  above  the 
sea. 

Country,  3  miles  from 
Manchester. 

Summit  of  Snowdon . . , 

Second  bottle  from 
Snowdon. 

Country ,  near  Man- 
chester   

Town  air   

Summit  of  Helvellyn  . . 

Town  air 


Balloon    voyage   over 
Cheshire  (9600  ft.). 

Town  air 

....Do 


Town  air 

Smnmit  of  Snowdon    . 

Summit  of  Helvellyn  . 


Collected  from  balloon; 

altitude,    15,000   ft. 

(first  phial) . 
Town  air 


Merde  Glace,  6000  ft. 
above  the  sea. 

SimplonPass,  6174  ft. 
Wengem  Alps,  6230  ft. 


Oxygen, 


p.  ct. 

20.70 

20.88 
20.25 


21.12 

20.97 
20.58 

20.6 

20.65 

.20.8 

20.59 
20.9 

20.7 

21.04 
20.63 
20.73 

20.7 

20.83 
20.8 

20.92 
20.44 

20.57 


20.59 


20.95 

20.2 

19.4 

19.98 

19.53 

20.45 

20.11 


Analyzed  on  May  28,  1826. 

•  Analysed  on  May  25, 1826. 

Collected  on  June  26,  1827. 


•  Analyzed  on  July  21,  1831,  or  17  days  later. 

•  All  analyzed  in  October,  1835. 

•  Duplicate. 


The  explosion  of  hydrogen  and  air  by  the  electric  spark,  as  originally 
proposed  by  Volta,  had  been  the  only  method  of  uniting  hydrogen  and 
oxygen  in  gas-analysis  up  to  1824,  when  Doebereinepi  announced  his  dis- 
covery  of  the  catalytic  action  of  platinum  sponge. 

*  Doeberemer,  Schweiggers  Journal  fur  Chemie  und  Physik,  1824, 42,  p.  60. 


History  op  Air-Analysis 


27 


On  a  trip  to  South  America  in  1825,  Boussingault^  made  observations 
on  the  oxygen  content  of  the  air  at  various  altitudes.  In  at  least  one 
analysis  he  used  platinum  sponge,  for  he  reports  that  air  taken  in  Novem- 
ber, 1826,  at  Mariquita,  in  the  valley  of  the  Magdalena,  at  an  altitude  of 
548  meters,  gave  with  platinum  sponge  20.77  per  cent  of  oxygen. 

Two  analyses  made  with  the  Volta  eudiometer  gave  results  as  follows : 

December  1826,  Ibagu6  (1323  meters)   20.7    per  cent. 

April  1825,  Santa  F6  de  Bogota  (2643  meters) 20.65  per  cent. 

Boussingault  concluded  that  his  observations  were  not  in  accord  with 
the  Dalton  hypothesis. 

Turner,  2  in  a  paper  read  before  the  Royal  Society  of  Edinburgh,  1824, 
reported  his  experiences  with  the  use  of  spongy  platinum  on  a  mixture 
of  air  and  hydrogen.  Three  experiments  gave  21.8,  22.3,  and  21.7  per 
cent  of  oxygen,  respectively.  Suspecting  the  purity  of  his  hydrogen,  he 
left  an  active  ball  of  spongy  platinum  in  contact  with  hydrogen  over 
night  and  made  6  tests  the  next  day.  The  results  were  20.3,  20.3,  20.7; 
21,  21.3,  and  21.7  per  cent  of  oxygen,  respectively,  the  mean  of  these  ex- 
periments being  20.88  per  cent;  he  assumes  21  per  cent  of  oxygen  as  the 
correct  value. 

Table  5. — Percentages  of  oxygen  obtained  by  Baumgartner  in  atmospheric  air. 


Date. 

Oxygen. 

Date. 

Oxygen. 

Date. 

Oxygen. 

1831 

p.ct. 

1831 

p.ct. 

1831 

p.ci. 

Sept.    24 

20.6 

Oct.      4 

21.1 

Oct.    14 

21.0 

Sept.    25 

21.4 

Oct.      5 

21.4 

Oct.    15 

20.9 

Sept.    26 

21.0 

Oct.      6 

21.3 

Oct.    16 

20.7 

Sept.    27 

20.9 

Oct.      7 

21.1 

Oct.    17 

21.0 

Sept.    28 

21.1 

Oct.      8 

20.9 

Oct.    18 

20.7 

Sept.    29 

21.2 

Oct.      9 

20.9 

Oct.    19 

20.8 

Sept.    30 

21.2 

Oct.    10 

20.9 

Oct.    20 

21.0 

Oct.       1 

21.4 

Oct.    11 

21.0 

Oct.    21 

21.0 

Oct.       2 

20.4 

Oct.    12 

20.7 

Oct.    22 

21.0 

Oct.       3 

21.3 

Oct.    13 

20.8 

Degen^  in  Stuttgart  likewise  used  platinum  sponge  and  found  in  out- 
door air  20.80,  20.88,  and  20.89  per  cent. 

Kupffer*  in  Kasan,  by  using  a  Volta  eudiometer  and  mixing  99  parts 
of  hydrogen  with  198  parts  of  air,  found  after  explosion  a  residue  of  171  to 
172  parts,  corresponding  to  21  to  21.2  per  cent  of  oxygen. 

The  appearance  of  cholera  in  Vienna  in  1831  led  to  an  exhaustive 
study  of  the  atmosphere  by  Baumgartner,^  who  analyzed  the  air  each  day 
from  September  24,  1831,  to  January  31,  1832,  by  means  of  the  Volta 
eudiometer.  Differences  between  analyses  on  the  same  sample  seldom 
varied  0.2  per  cent. 

*  Boussingault,  Annales  de  Chimie  et  de  Physique,  1841, 3rd  ser.,  I,  p.  354. 
'  Turner,  abstracted  in  Boston  Journal  of  Philosophy,  1825, 2,  p.  238. 

*  Degen,  Poggendorff 's  Annalen  der  Physik  and  Chemie,  1833,  27,  p.  557. 

*  Kupffer,  Annales  de  Chimie  et  de  Physique,  1829, 4 1 ,  p.  423. 

'  Baumgartner,  Medicinische  Jahrbiicher  des  k.  k.  osterreichischen  Staates,  1832, 
12,  p.  83. 


Composition  of  the  Atmosphere 


The  results  for  the  first  month,  which  are  fairly  representative  of  the 
remainder  of  the  study,  are  given  in  table  5. 

The  use  of  a  metal  to  absorb  oxygen  was  first  suggested  by  Scheele,^ 
who  employed  metallic  iron.  A  Spaniard,  Luzuriaga,^  in  1784,  used  lead, 
but  his  results  are  not  available. 

The  first  practical  use  of  a  metal  as  an  oxygen  absorbent  in  air-analysis 
was  made  by  Theod.  de  Saussure,^  who  employed  lead  shavings  moistened 
with  a  very  little  water.  After  shaking  them  3  hours,  he  found  that  the 
absorption  was  complete,  de  Saussure  criticized  the  earlier  methods, 
since  so  many  divergent  results  were  obtained  by  different  workers,  con- 
sidering the  Volta  eudiometer  especially  open  to  criticism,  as  there  was 
always  danger  of  an  impurity  in  the  hydrogen.  He  believed  the  lead 
method,  though  not  so  convenient,  to  be  much  more  accurate.  A  state- 
ment of  his  results  is  given  in  table  6. 

Table  6. — Results  obtained  by  de  Saussure  with  the  lead  method. 


Place. 


Date. 


Lake  of  Geneva  . . 
Chambeisy^ 

Do 

Street  in  Geneva  . 
Chambeisy    

Do 

Do 

Lake  of  Geneva  . . 
Chambeisy    

Do 

Do 

Do 

Do 

Lake  of  Geneva    . . 

Average  of  all 
Carbon  dioxide 
Oxygen  in  100 
parts  of  air  . 


July 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Sept. 
Sept. 
Nov. 
Nov. 
Dec. 
Dec. 
Dec. 
Dec. 


18 
3 
16 
25 
27 
27 
13 
13 
5 
21 
13 
24 
28 
29 


Weather. 


Quiet  and  clear 

Clear;  NE.  wind 

Clear;  light  SW.  wind     

Clear;  light  NE.  wind     

Rainy;  strong  SW.  wind 

...Do 

Clear;  light  NE.  wind     

...Do 

Overcast;  calm 

Overcast;  strong  NE.  wind 

Quiet;  foggy    

Overcast;  strong  NE.  wind    . .  . . 

Clear;  strong  NE.  wind    

Partly  overcast;  light  SW.  wind, 


Oxygen  and 
carbon  diox- 
ide absorbed. 


p.  ct. 
21.08 

20.98 

21.03 

21.03 

21.13 

21.15 

21.08 

21.09 

20.98 

21.086 

21.006 

21.1 

21.0 

21.04 


21.05 
.04 


21.01 


*  Meadow  1  league  from  Geneva. 

From  these  results  one  concludes  that  de  Saussure  determined  carbon 
dioxide  and  oxygen  together  and  subsequently  deducted  the  carbon  diox- 
ide.   His  results  show  surprising  constancy  in  the  oxygen  content  of  the  air. 

Dupasquier/  employing  the  alkaline  ferrous  hydroxide  originally  em- 
ployed by  Scheele,  found  that  normal  air  always  gave  21  per  cent.  Some- 
what later,  Brunner^  reverted  to  the  precipitated  ferrous  hydroxide 
method,  but  reported  no  air-analyses. 

^  Scheele,  Air  and  Fire,  London,  1780,  p.  13. 
2  See  Kopp's  Geschichte  der  Chemie,  1845, 3,  p.  211. 
»  de  Saussure,  Annalen  der  Physik,  1836,  ser.  2,  8,  p.  171. 
*  Dupasquier,  Annales  de  Chimie  et  de  Physique,  1843,  3d  ser.,  9,  p.  247. 
« Brunner,  Poggendorff's  Annalen  der  Physik  und  Chemie,  1848,  Erganzun: 
2,  p.  509. 


History  of  Air-Analysis 


29 


THE  FOUNDATIONS  OF  MODERN  AIR-ANALYSIS. 

About  1840,  Bunsen  in  Marburg,  working  with  that  marvelous  tech- 
nique that  characterized  all  of  his  chemical  observations,  developed  to  the 
highest  degree  the  explosion  method  with  hydrogen  for  determining  oxy- 
gen. A  preliminary  description  of  much  of  his  technique  was  published 
in  an  article  by  Kolbe.^  Bunsen's  apparatus  is  there  described  and  to 
demonstrate  the  accuracy  of  the  apparatus  several  analyses  of  atmos- 
pheric air  were  made  in  1846.  These  analyses  with  slightly  corrected 
figures  are  given  again  in  detail  in  Bunsen's  book,^  and  are  reproduced 
in  table  7. 

Bunsen  expressed  the  belief  that  the  composition  of  the  air  could  be 
determined  much  more  accurately  if  the  eudiometer  readings  were  re- 
peated from  hour  to  hour.  One  such  analysis  made  on  May  31,  1847, 
gave  20.964  per  cent. 

Table  7. — Results  obtained  by  Bunsen  with  the  hydrogen-explosion  method. 


Date. 

Oxygen. 

Date. 

Oxygen. 

Date. 

Oxygen. 

1846 
Jan.     9 
Jan.    11 

p.ct. 

S  20.970 

I  20.963 

20.927 

1846 

Jan.   22 
Jan.  24 
Jan.   26 
Jan.   28 
Jan.   30 

{  20.919 

I  20.880 
{  20.921 
I  20.943 
{  20.927 
?  20.934 
<  20.928 
I  20.911 
{  20.889 
I  20.892 

1846 

Feb.     1 

Feb.     3 

Feb.     5 
Feb.     8 

{  20.840 

I  20.859 
{  20.925 
}  20.940 
i  20.937 
}  20.952 
20.953 

Jan.    13 
Jan.    14 

Jan.    18 
Jan.  20 

20.914 

20.950 

With  another 

eudiometer 

^  20.906 
I  20.928 
{  20.927 
I  20.927 

These  figures  of  Bunsen  marked  a  great  advance  in  accuracy,  and  it  is 
important  to  note  that  Bunsen's  method  subsequently  received  exten- 
sive use  by  different  investigators.  An  extract  from  a  letter  written  by 
Bunsen  to  J.  J.  Berzelius  on  November  3,  1846,  is  of  especial  interest  in 
connection  with  the  main  problem  of  this  memoir. ^ 

Ich  habe  zunachst  meine  Aufmerksamkeit  auf  einige  Fragen  iiber  die  Zusammen- 
setzung  der  atmospharischen  Luft  gerichtet  und  befinde  mich  im  Besitz  von  mehr  als 
300  gleichzeitig  in  Marburg,  Copenhagen,  Reykjavik,  in  der  Nahe  des  Polarkreises  und 
auf  dem  atlantischen  Ocean  aufgefanger,  und  in  zugeschmolzenen  Glasgefassen  be- 
wahrter  Luft  proben,  die  zu  Analysen  nach  einer  Methode  ausreichen,  deren  Scharfe 
und  Sicherheit  kaum  etwas  zu  wunschen  ubrig  lasst,  wie  die  nachstehenden  zur  Priifung 
dieser  methode  in  verflossenen  Winter  angestellten  Versuche  beweisen. 

*Kolbe,  "Eudiometer,  Eudiometrie"  in  the  Handworterbuch  der  Chemie,  Liebig, 
Poggendorfif  and  Wohler,  1842,  2,  p.  1050. 

•  Bunsen,  Gasometrische  Methoden,  Braunschweig,  1857,  p.  77. 

•  Gesammelte  Abhandlungen  von  R.  Bunsen,  Leipzig,  1904,  2,  p.  4. 


30  Composition  of  the  Atmosphere 

Unfortunately  nowhere  in  Bunsen's  subsequent  publications  do  we 
find  any  record  of  the  analyses  of  this  large  number  of  samples  of  air, 
and  obviously  the  pressure  of  other  work  prevented  his  carrying  out 
this  inquiry.  It  is  greatly  to  be  regretted  that  with  his  masterful  tech- 
nique such  analyses  could  not  have  been  made. 

Although  Lavoisier  had  shown  that  when  phosphorus  was  burned  in 
air  there  was  an  increase  in  weight  corresponding  to  the  diminution  in 
volume  of  the  air,  nevertheless  no  air-analyses  were  based  upon  gravi- 
metric determinations  until  the  appearance  in  1833  and  1834  of  the  unique 
method  of  Brunner^  in  Berne.  Brunner  devised  a  plan  of  passing  a 
volume  of  air  through  a  tube  that  contained  some  suitable  absorbent  for 
oxygen  which  could  be  weighed.  All  previous  determinations  had  been 
made  over  water,  or  occasionally  mercury,  upon  relatively  small  volumes 
of  air  confined  in  glass  tubes,  eudiometers,  etc.,  but  with  Brunner's 
method,  a  considerably  larger  volume  of  air  could  be  used.  Furthermore, 
it  was  possible  by  this  process  to  measure  likewise  the  amount  of  nitrogen 
remaining  in  the  gas,  and  thus  make  a  determination  not  only*of  oxygen 
by  weight,  but  of  nitrogen  by  volume.  After  a  number  of  preliminary 
experiments  made  with  iron  and  with  copper,  Brunner  finally  decided 
upon  phosphorus  as  the  best  absorbent.  With  perfectly  dry  phos- 
phorus and  a  very  moderate  air-current,  he  found  that  oxygen  was 
rapidly  and  quantitatively  absorbed. 

In  1833  Brunner  made  a  series  of  experiments  in  Berne  in  which:  he 
determined  the  average  oxygen  content  of  the  air  as  21.0705  per  cent. 
The  agreement  was  usually  within  0.1  per  cent,  although  occasionally  the 
variation  was  as  high  as  0.2  per  cent.  Of  interest,  also,  is  the  fact  that  he 
analyzed  air  taken  on  the  Faulhorn  on  July  18,  19,  and  20  of  the  same 
year;  from  14  determinations  he  found  the  oxygen  varying  from  20.75  to 
21.11  per  cent,  the  average  of  all  being  20.915.  Eight  years  later,  in 
July  1841,2  Brunner  made  7  experiments  in  the  same  manner  as  those 
made  at  Berne,  and  found  ranges  from  20.75  to  20.867  per  cent,  with  an 
average  of  20.821  per  cent.  The  fact  that  this  latter  value  is  very  much 
less  than  those  found  8  years  before  is  explained  by  Brunner  on  the  ground 
that  there  was  probably  an  error  in  the  measurement  of  the  size  of  the 
vessel  used  in  the  earher  experiments.  Brunner's  article  is  particularly 
valuable,  as  it  contains  a  critical  discussion  of  methods  and  of  the  limit 
of  accuracy  of  the  various  methods  that  had  been  proposed  for  absorbing 
oxygen. 

While  Brunner  had  successfully  weighed  the  oxygen  absorbed  from  the 
air,  he  had  always  measured  the  volume  of  nitrogen.  In  1841  Dumas  and 
Boussingault'  published  a  research  which  in  plan  was  quite  similar  to 
that  of  Brunner,  except  that  they  not  only  weighed  the  oxygen  but  like- 

1  Brunner  Poggendorfif's  Annalen  der  Physik  und  Chemie,  1833,  ser.  2,  27,  p.  1: 
al80,tM.,  1834,ser.2,3l,p.  1.  t      tf      > 

«  Brunner,  Annales  de  Chimie  et  de  Physique,  ser.  3, 1841, 3,  p.  305. 
»  Dumas  and  Boussingault,  Annales  de  Chimie  et  de  Physique,  ser.  3,  1841,  3,  p.  257. 


History  of  Air-Analysis 


31 


wise  the  nitrogen.  By  using  large  glass  vessels  which  could  be  evacuated 
and  passing  the  air  over  heated  metaUic  copper,  they  absorbed  the  oxy- 
gen by  the  copper,  weighing  the  vessel  before  and  after  absorption,  thus 
giving  a  true  weight  of  the  nitrogen  left  behind.  The  method  was  ob- 
viously best  used  by  its  illustrious  devisers,  since  it  was  much  more  tech- 
nical and  difficult  to  carry  out  than  any  previously  suggested.  By  means 
of  two  apparatus,  simultaneous  experiments  were  made  in  1841.  The 
percentage  volumes  of  oxygen  found  are  given  in  table  8.  These  samples 
were  all  taken  during  very  clear  and  beautiful  weather,  and  as  a  control 
a  sample  was  taken  on  May  29,  1841,  during  rain.  The  result  was  essen- 
tially that  found  during  the  clear  weather,  viz,  20.817  per  cent  of  oxygen. 
Table  8. — Percentages  of  oxygen  in  air  analyzed  by  Du  mas  and  Boussingault. 


Date. 

First 
analysis. 

Second 
analysis. 

Average. 

1841 

Apr.  27 

Apr.  28 

Apr.  29 

Average  . . 

V.ct. 

20.73 
20.83 
20.83 

V.ct. 

20.73 
20.88 
20.84 

V.ct. 

20.73 
20.86 
20.83 

20.80 

20.82 

20.81 

Although  the  experimental  evidence  of  Gay-Lussac  and  von  Hum- 
boldt, as  well  as  the  earlier  observations  of  Boussingault  in  South  America, 
agreed  perfectly  with  the  more  recent  work  of  Dumas  and  Boussingault, 
nevertheless,  owing  to  the  importance  of  the  Dalton  hypothesis,  Dumas 
and  Boussingault  decided  upon  making  some  analyses  of  air  taken  from 
the  Faulhorn.  By  previous  arrangement  with  Brunner  in  Berne,  a  series 
of  experiments  was  planned  in  which  samples  of  air  would  be  taken  simul- 
taneously in  Paris,  Berne,  and  on  the  Faulhorn.  These  latter  were  col- 
lected by  means  of  large  evacuated  glass  balloons  which  were  sent  by 
Dumas  from  Paris.  In  Berne,  Brunner  operated  with  his  method  pre- 
viously described.  The  results  of  these  comparisons,  which  represent  the 
first  cooperative  investigation  of  any  magnitude  on  the  composition  of 
the  air,  are  given  in  table  9. 

Table  9. — Percentages  of  oxygen  in  air  analyzed  by  Dumas  and 
Boussingault,  and  by  Brunner. 


Date. 

Paris. 

Faulhorn. 

Berne. 

July  20 

July  21 

July  24 

Aug.  7 

Average  . . 

V.ct. 

20.85 
20.80 

20.87 

V.ct. 

20.77 

20.89 

{  20.76 

/  20.67 

20.78 

V.ct. 

20.80 
20.70 
20.78 
20.77 

20.84 

20.78 

20.76 

While  there  is  a  difference  between  the  samples  in  Paris  and  the  sam- 
ples in  Berne  and  on  the  Faulhorn,  it  is  important  to  note  that  somewhat 


32 


Composition  of  the  Atmosphere 


later  some  50-liter  samples,  which  were  taken  in  Paris  and  analyzed 
with  the  very  greatest  care,  showed  variations  equally  as  great;  thus, 
on  September  20  the  percentage  was  20.875,  while  on  September  22  it 

was  20.709. 

Brunner's  method  was  used  successfully  by  Verver^  m  Gromngen  m 
May  and  August  1838.     As  a  result  of  45  analyses,  he  found  the  average 
oxygen  content  of  carbon-dioxide  and  water-free  air  to  be  20.864  per  cent. 
The  oxygen  percentages  obtained  by  Verver  are  given  in  table  10. 
Table  10.— Percentages  of  oxygen  in  air  analyzed  by  Verver. 


Date. 

Oxygen. 

Date. 

Oxygen. 

1          Date. 

Oxygen. 

1838 

p.cL 

1838. 

p.ct. 

1838. 

p.ct. 

May  21 

21.00 

May  24 

21.09 

Aug.    2 

20.96 

May  21 

20.70 

May  24 

20.88 

Aug.    3 

20.70 

May  21 

20.80 

May  24 

20.76 

Aug.    3 

20.80 

May  21 

20.85 

May  25 

21.10 

Aug.    3 

21.05 

May  22 

20.79 

May  25 

21.06 

Aug.    3 

20.90 

May  22 

21.00 

May  25 

21.02 

Aug.    3 

20.80 

May  22 

20.77 

May  25 

21.06 

Aug.    5 

20.60 

May  22 

20.95 

Aug.    1 

20.90 

Aug.    5 

20.70 

May  23 

20.93 

Aug.    1 

21.08 

Aug.    5 

20.65 

May  23 

20.91 

Aug.    1 

20.90 

Aug.    5 

20.64 

May  23 

20.85 

Aug.    2 

20.91 

Aug.    5 

20.90 

May  23 

20.90 

Aug.    2 

20.80 

Aug.    5 

20.90 

May  23 

20.94 

Aug.    2 

20.80 

Aug.    6 

20.70 

May  24 

20.82 

Aug.    2 

20.90 

Aug.    6 

20.70 

May  24 

20.67     j 

Aug.    2 

20.80 

Aug.    6 

20.70 

Dumas  and  Boussingault  were  at  first  inclined  to  believe  that  since 
their  results,  those  of  Berger,  Gay-Lussac,  and  von  Humboldt,  the  earlier 
results  of  Boussingault,  and  the  results  of  Brunner,  all  agreed  so  remark- 
ably, the  composition  of  the  atmosphere  was  uniform.  Subsequent  ex- 
periments made  in  combination  with  Brunner  on  the  air  from  the  Faul- 
horn,  Paris,  and  Berne  showed  that  there  were  also  differences;  they  ac- 
cordingly modified  their  conception  and  said  that  although  on  the  whole 
the  composition  of  the  air  was  constant,  nevertheless  there  must  be  cer- 
tain variations  which  might  occur. 

The  demonstrated  accuracy  of  the  method  of  Dumas  and  Boussingault 
led  to  its  extensive  use  by  other  observers.  In  1841  and  1842  Lewy  made 
analyses  of  air  from  the  North  Sea,  the  court  of  the  Polytechnic  School, 
Copenhagen,  and  the  coast  at  Elsinore.^  In  November  and  December  of 
1841,  five  analyses  of  air  in  Copenhagen  were  made,  giving  20.82,  20.83, 
20.78,  20.81,  and  20.84  per  cent  of  oxygen,  respectively,  with  an  average 
of  20.816  per  cent.  The  author  points  out  that  these  results  agreed  per- 
fectly with  those  obtained  by  Dumas  and  Boussingault  in  their  analyses 
of  the  air  collected  in  Paris  and  on  the  Faulhorn,  as  well  as  with  those 
obtained  by  Stas  in  Brussels,  Marignac  in  Geneva,  Brunner  in  Berne,  and 
Verver  in  Groningen. 

^  Verver,  Bulletin  des  Sciences  Physiques  et  Naturelles  en  N6erlande,  1840,  p.  191. 
» Lewy,  Annales  de  Chimie  et  de  Physique,  1843,  ser.  3,  8,  p.  425. 


History  of  Air-Analysis  33 

During  August  1841,  on  a  journey  from  Paris  to  Copenhagen,  he 
collected  samples  on  the  North  Sea,  the  results  being  20.46,  20.42,  20.45, 
and  20.43  per  cent,  with  an  average  of  20.44  per  cent.  His  low  values 
may  possibly  be  ascribed  to  an  error  in  weighing  the  glass  balloon  used. 
Analyses  were  also  made  of  air  taken  at  Elsinore  on  the  coast.  Three 
samples  taken  on  February  18,  1842,  gave  20.84,  20.83,  and  20.84  per 
cent  respectively.  The  average  was  20.837  per  cent.  On  the  return 
journey  from  Copenhagen  to  France,  5  samples  of  air  taken  on  the  sea 
were  collected,  the  percentages  of  oxygen  being  20.88,  20.91,  20.89,  21.01, 
and  20.84,  with  an  average  of  20.907. 

Lewy  also  reports  analyses  of  samples  taken  at  Guadeloupe  and  ana- 
lyzed in  Paris.  The  results  show  abnormally  high  carbon-dioxide  values 
and  low  oxygen  contents.  When  computed  on  the  basis  of  carbon- 
dioxide-free  air,  the  oxygen  content  in  9  samples  varies  from  20.51  to 
20.93  per  cent.  The  author  is  inclined  to  attribute  the  exceptionally 
high  carbon-dioxide  content  to  the  nearby  volcanoes. 

In  Geneva,  Marignac^  found  on  three  different  days,  in  January  and 
February  1842,  20.81,  20.80,  and  20.77  per  cent  of  oxygen,  with  an  average 
of  20.799  per  cent.  Meanwhile,  Stas^  in  Brussels  found  in  12  different 
experiments  during  1842  a  minimum  of  20.84  per  cent  and  a  maximum 
of  20.87  per  cent,  but  the  author  points  out  two  analyses  with  no  error 
that  could  be  accounted  for  in  which  the  results  showed  20.90  and  20.93 
per  cent.  In  general,  however,  Marignac,  Lewy,  and  St  as,  all  using  the 
method  of  Dumas  and  Boussingault,  obtained  results  that  agreed  with 
those  obtained  by  the  latter  investigators. 

In  studying  respiration,  Marchand^  reported  air-analyses  made  in 
Halle  at  10  different  times.  The  method  was  similar  to  that  of  Du- 
mas and  Boussingault.  The  percentages  of  oxygen  obtained  were  as 
follows: 


per  cent. 

1 20.99 

2 20.97 

3 20.98 

4 20.90 

5 20.96 


per  cent. 

6 20.89 

7 20.98 

8 20.99 

9 21.02 

10 21.03 


The  average  of  these  values,  20.97  per  cent,  was  employed  by  him  as 
indicating  the  composition  of  normal  air. 

Two  years  later,  Marchand*  published  two  analyses  of  outdoor  air 
in  Halle  which  were  made  by  the  hydrogen-explosion  method  with  results 
as  follows:  8  a.m.,  20.920  per  cent;  8  p.m.,  20.912  per  cent. 

In  the  attempt  to  establish  some  relationship  between  the  com- 
position of  the  air  and  the  invasion  of  cholera,  at  least  two  investi- 
gations on  the  oxygen  content  of  the  atmospheric  air  during  a  cholera 

1  Marignac,  reported  by  Dumas  in  Comptes  rendus,  1842, 14,  p.  380. 

2  Stas,  Comptes  rendus,  1842,  14,  p.  570. 

'  Marchand,  Journal  fiir  praktische  Chemie,  1848, 44,  p.  1. 
*  Marchand,  Journal  fiir  praktische  Chemie,  1850, 49,  p.  449. 


34 


Composition  of  the  Atmosphere 


epidemic  are  reported  in  the  literature/  i.e.,  those  of  Baumgartner^  and 
Laskowsky.^ 

Employing  Brunner's  method,  Laskowsky  in  Moscow  made  a  num- 
ber of  analyses  of  air  during  the  cholera  epidemic.  The  results,  which 
are  given  in  table  11,  show  a  variation  of  0.16  per  cent  of  oxygen,  which  the 
author  maintains  is  not  far  from  the  results  of  Dumas  and  Boussingault, 
who  report  variations  of  0.19  per  cent.  He  concludes  that  the  air  in 
Moscow  during  the  time  of  the  cholera  was  normal. 

Table  11. — Air-analyses  made  by  Laskowsky  in  Moscow  during  the  cholera  in  18^7. 


Date. 

Time. 

Oxygen. 

Date. 

Time. 

Oxygen. 

1847 

Nov.    3 

Nov.    3 

Nov.    4 

Nov.    4 

Nov.    7 

Nov.    7 

Nov.    8 

Nov.    8 

Nov.    9 

Noon    

Evening 

Noon    

Evening 

Noon    

Evening 

Noon    

Evening 
Noon    

20.88 
20.76 
20.73 
20.85 
20.89 
20.82 
20.82 
20.76 
20.88 

1847. 

Nov.    9 

Nov.  10 

Nov.  10 

Nov.  11 

Nov.  11 

Maximum . 
Minimum  . 
Average  . . 

Evening     . . 

Noon    

Evening     . . 

Noon    

Evening     . . 

26.77 

20.80 
20.87 
20.82 
20.77 

20.89 
^.73 
20.82 

Adding  oxide  of  manganese  to  the  reduced  copper  of  the  Dumas  and 
Boussingault  method  to  increase  its  absorbing  action,  Deville  and  Gran- 
deau*  determined  the  oxygen  in  a  number  of  samples  of  air  for  May  and 
June  of  1859,  and  found  as  an  average  20.88  per  cent. 

An  ingenious  use  of  an  ammoniacal  solution  of  copper  chloride  as  an 
absorbent  for  oxygen  was  made  by  Doyere^  in  connection  with  studies 
on  respiration.  As  the  result  of  several  analyses  by  this  and  other  meth- 
ods, Doyere  reports  that  the  percentage  of  oxygen  in  air  is  about  20.5  to 
20.7,  but  the  research  does  not  inspire  confidence. 

Employing  an  exceptionally  accurate  hydrogen  eudiometer  designed 
primarily  for  use  in  their  classical  respiration  experiments,  Regnault  and 
Reiset  reported  in  a  preliminary  communication  in  1848^  a  large  number 
of  analyses  that  were  made  during  the  three  preceding  years,  1845,  1846; 
and  1847,  in  Paris,  as  well  as  near  Dieppe.  All  of  these  analyses  showed 
an  oxygen  content  between  20.85  and  20.97  per  cent.  In  the  report  of 
their  experiments  on  the  respiration  of  animals,^  the  authors  give  a  com- 

» The  early  observations  of  Davidson,  who  found  67  per  cent  of  vital  air  in  Mar- 
tinique during  an  epidemic  of  yellow  fever,  are  only  of  historic  interest.  (Cited  by 
Russell,  Transactions  of  the  Sanitary  Institute,  1893,  13,  p.  232.) 

'  Baumgartner,  loc.  cit. 

»  Laskowsky,  Liebig's  Annalen  der  Chemie  und  Pharmacie,  1850,  75,  p.  176. 

*  Deville  and  Grandeau,  Comptes  rendus,  1859,  48,  p.  1103. 
^  » Doyere,  Annales  de  Chimie  et  de  Physique,  1850,  3d  ser.,  28,  p.  5.  Among  the 
innumerable  observations  on  the  composition  of  the  air  made  by  Scheele,  it  is  interesting 
to  note  that  he  found  that  one-third  of  the  air  was  absorbed  by  an  ammoniacal  solution 
of  copper.  (See  Scheele,  Efterlemnade  bref  och  anteckningar.  Edited  by  A.  E.  Nor- 
denskiold,  Stockhohn,  1892,  p.  58.) 

« Regnault  and  Reiset,  Comptes  rendus,  1848, 26,  p.  6. 
Regnault  and  Reiset,  Annales  de  Chimie  et  de  Physique,  1848,  3d  ser.,  26,  p.  299. 


History  of  Air-Analysis 


35 


plete  description  of  their  eudiometer,  and  report  6  air-analyses  made 
from  one  sample  of  carbon-dioxide-free  air,  in  order  to  show  the  accuracy 
of  the  apparatus.  The  results  obtained  were  20.936,  20.940,  20.932, 
20.960,  20.946,  and  20.941  per  cent  of  oxygen,  the  variation  being  0.028 
per  cent. 

Table  12. — RegnauWs  analyses  of  air  collected  in  Paris. 


Date. 


1847. 

Dec.  24 


Dec.  24 

Dec.  24 
Dec.  28 


Dec.  28 

Dec.  29 
Dec.  29 

Dec.  30 

Dec.  30 
Dec.  31 

Dec.  31 
Dec.  31 
Dec.  31 

Dec.  31 
Dec.  31 

1848. 

Jan.  1 
Jan.     3 


Place. 


Oxygen. 


Balcony,  College  of 
France 

....Do 

....Do 

Top  of  Pantheon   .  . 
Top   of   Pantheon 

(snow) 

Observatory,  College 

of  France 

Place  de  la  Concorde 
Observatory,  College 

of  France 

...Do 

...Do 

...Do 

Top  of  the  Pantheon 

Choisy-le-Roi 

Esplanade    de   Vin- 

cennes 

...Do 

Over  a  cornfield . . . 

Court,  College  of 
France 

Observatory,  College 
of  France 


p.ct. 

20.987 
20.952 
20.957 
20.999 
20.962 

20.963 
20.956 
20.939 
20.953 

20.948 
20.939 
20.930 
20.984 
20.967 
20.949 

20.959 
20.966 

20.945 
20.947 
20.980 
20.992 


20.913 
20.934 


Date. 


1848. 

Jan.    4 


Jan. 
Jan. 
Jan. 
Jan. 
Jan. 


Jan.  10 
Jan.  11 
Jan.  12 
Jan.  12 

Jan.  13 

Jan.  14 
Jan.  14 
Jan.  15 

Jan.  15 
Jan.  15 
Jan.  15 

Jan.  15 
Jan.  15 

Jan.  15 
Jan.  15 


Place. 


Observatory,  College 
of  France 

....Do 

....Do 

....Do 

Choisy-le-Roi   

Observatory,  College 
of  France 

...Do 

...Do 

...Do 

Choisy-le-Roi   


Observatory,  College 

of  France 

...Do 

Pantheon 

Observatory,  College 

of  France 

Versailles 

Do 

Do 


.Do 
.Do 

.Do 
.Do 


Oxygen. 


p.  ct. 

20.929 
20.948 
20.943 
20.956 
20.948 

20.981 
20.948 
20.957 
20.963 
20.947 

20.970 
20.968 
20.952 
20.953 

20.986 
20.936 
20.922 
20.948 

20.954 
20.992 
20.993 

20.998 

20.952 


It  is  to  Regnault  that  we  are  indebted  for  the  first  extensive  inter- 
national investigation  on  the  composition  of  the  air.  This  carefully 
planned  cooperative  investigation  was  in  part  disturbed  by  the  political 
differences  in  Europe  during  1848,  but  in  spite  of  the  difficulties  encoun- 
tered, Regnault  finally  succeeded  in  getting  together  a  large  number  of 
samples,  which  he  analyzed. ^  Air  was  collected  in  Paris  and  other  parts 
of  France,  in  Berlin,  Madrid,  Switzerland,  on  the  Mediterranean  Sea,  on  the 
Atlantic  Ocean,  in  Ecuador,  on  the  coast  of  Africa,  in  India,  and  on  the 
Pacific  and  Arctic  Oceans,  thus  representing  by  far  the  most  extensive 
investigation  on  the  composition  of  atmospheric  air  that  has  ever  been 
undertaken.  Indeed,  it  may  be  stated  that  no  subsequent  investiga- 
tion has  approached  it  in  completeness  with  regard  to  the  geographical 
collection  of  samples.  Regnault  made  arrangements  to  have  these  sam- 
1  Regnault,  Annales  de  Chimie  et  de  Physique,  1852, 3d  ser.,  36,  p.  385. 


36 


Composition  of  the  Atmosphere 


pies  collected  on  the  1st  and  15th  of  each  month  at  about  the  hour  of 
true  midday  in  each  place.  The  samples  were  then  sent  to  Paris,  where 
they  were  analyzed  by  explosion  with  hydrogen  in  the  apparatus  used 
for  analyzing  the  samples  of  Paris  air. 

About  100  analyses  were  made  of  air  collected  in  Paris  or  its  suburbs, 
the  larger  number  being  taken  at  the  observatory  of  the  College  of  France. 
A  part  of  the  results  are  given  in  table  12,  showing  the  variations  on  the 
different  days  and  the  accuracy  of  the  analyses  made  on  the  same  sample 
as  indicated  by  the  close  agreement  of  the  duplicate  determinations. 

The  smallest  amount  of  oxygen  found  was  20.913  per  cent,  the  largest 
20.999  per  cent,  and  the  general  average,  20.96  per  cent.  The  extreme 
difference,  0.086  per  cent,  is  greater  than  the  errors  resulting  from  the 
experiments  themselves,  for  this  rarely  exceeds  0.02  per  cent.  Regnault 
concludes  that  the  absolute  change  is  so  small  that  one  can  easily  attrib- 
ute this  to  local  alterations  which  would  be  frequently  found  in  the  center 
of  large  cities.  He  notes  further  that  the  variations  found  at  different 
hours  of  the  same  day  are  no  smaller  than  the  variations  between  days. 

The  results  of  the  analyses  of  air  collected  at  other  points  in  France  are 
given  in  table  13. 

Table  13. — RegnaiUt's  analyses  of  air  collected  in  France  outside  of  Paris. 


Montpellier. 

Lyon. 

St.  Martin-aux-Arbre.s, 
Normandy. 

Date. 

Oxygen. 

Date. 

Oxygen. 

Date. 

Oxygen. 

1848. 

Feb.     1.... 

Feb.  15... 

Mar.  15.... 

Apr.     1 . .  . . 
Apr.  15.... 

p.ct. 

{  20.929 

}  20.948 

20.962 

i  20.959 

/  20.968 

20.940 

20.952 

1848. 

Feb.     1 . . . . 
Feb.  15.... 
Mar.  15.... 

p.ct. 

20.966 
20.930 
20.918 

1848. 

Feb.  29  ... . 

20.952 

Table  14. — RegnauU's  analyses  of  air  collected  in  Berlin. 


Date. 

Oxygen. 

Date. 

Oxygen. 

Date. 

Oxygen. 

1848. 

p.  ct. 

1848. 

p.  ct. 

1849. 

p.  ct. 

Feb.      1 

20.967 

Aug.  16 ... . 

20.910 

Feb.  15 ... . 

20.993 

Feb.  15.... 

20.959 

Sept.  15 

20.943 

Mar.  15 ... . 

20.980 

Mar.  15 ..  .. 

20.956 

Oct.     1 . .  . . 

20.976 

Apr.     1 

20.962 

Apr.     1 . .  . . 

20.958 

Oct.   15 ... . 

20.986 

Apr.  16 

20.947 

Apr.  15 ... . 

20.963 

Nov.    2.... 

20.936 

May    3.... 

20.976 

May    1 . .  . . 

J  20.941 
}  20.953 

Nov.  15 ... . 

20.946 

May  17 ... . 

20.967 

May  15 ... . 

Dec.     1 . .  . . 

20.996 

June    3  . .  . . 

20.967 

20.937 

Dec.  15 

20.919 

June  15 ... . 

20.966 

June  15 ... . 

J  20.943 
)  20.933 

1849. 

July     1 . .  . . 

20.998 

Jan.     1 

20.981 

July     1.... 

20.908 

Jan.    15 

20  962 

July   15 ... . 

20.903 

j  Feb.     3.... 

20.973 

1 

Samples  were  also  collected  at  noon  in  Berlin  by  Magnus  from  Feb- 
ruary 1,  1848,  to  July  1,  1849;  at  the  Madrid  Observatory  in  1848;  and  at 


History  of  Air-Analysis 


a? 


different  places  in  Switzerland;  the  results  are  reported  in  tables  14,  15, 
and  16,  respectively. 

Table  15. — RegnauU's  analyses  of  air  collected  at  Madrid. 


Date. 

Oxygen. 

Date. 

Oxygen.         1 

1848. 

p.ct. 

1848. 

p.  ct. 

Feb.  15 ... . 

20.922 

Aug.  15 ... . 

20.963 

Mar.    1 . .  . . 

20.953 

Sept.    1.... 

{  20.982 
I  20.964 

May  15.... 

20.973 

June  15 

20.916 

Sept.  15 ... . 

20.975 

July  15.... 

20.924 

Oct.     1 . .  . . 

20.970 

Aug.    1.... 

20.974 

Table  16. — RegnaulVs  analyses  of  air  collected  in  Switzerland. 


Date. 


1848. 

Jan.  15 
Feb.     1 

Feb.     1 

Apr,  1 
Apr.  1 
June  15 
July  1 
July  15 
Aug.  1 
Aug.  15 


Place. 


Mont  Saleve } 

Obs.  of  Geneva. . . 

Mont  Saleve 

Obs.  of  Geneva. . . 

Mont  Sal^ve 

Obs.  of  Geneva. . . 

....Do 

....Do 

....Do 

....Do 


Oxygen. 


p.  ct. 

20.940 
20.953 
20.946 
20.935 
20.963 
20.957 
20.920 
20.928 
20.956 
20.903 
20.935 
20  937 
20.961 


Date. 


1848. 

Sept.  1 
Sept.    6 

Sept.  8 
Oct.  1 
Nov.  1 
Nov.  15 
Dec.  1 
Dec.  15 

1849. 

Jan.  15 
Feb.  1 
Feb.   15 


Place. 


Obs.  of  Geneva 

Montanvert  (valley 

of  Chamounix) . . 

Mont  Buet  (Savoy) 

...Do 

Obs.  of  Geneva .... 

...Do 

....Do 

....Do 

....Do 

....Do 

....Do 


Oxygen. 


p.  ct. 
20.924 

20.963 
20.930 
20.981 
20.969 
20.990 
20.955 
20.913 

20.959 
20.993 
20.982 


The  percentage  of  oxygen  in  these  different  samples  of  air  collected  in 
various  parts  of  Europe  ranged  from  20.903  to  21,  that  is  to  say,  it  had 
approximately  the  same  limit  of  variation  as  the  air  collected  in  Paris. 

Regnault  fortunately  secured  the  cooperation  of  a  number  of  travelers, 
and  hence  was  able  to  extend  his  observations  considerably.  The  results 
are  given  in  tables  17  to  20. 


Table  17. — Analyses  of  air  collected  on  the  Mediterranean  Sea. 


Date. 

Place. 

Oxygen. 

Date. 

Place. 

Oxygen. 

1851. 
May    4 

May  20 
May  21 
May  22 
May  22 
Mav24 
May  25 

May  27 

May  27 

At  sea,  SE.of  Minor- 
ca, lat.  38**  18' N.; 
long.  1^16'  E 

Toulon  harbor    

....Do 

p.ct. 

20.970 
20.912 
20.931 
20.951 
20.970 
20.950 
20.960 
20.854 
20.872 
20.979 

1851. 

May  28 
June    8 

June    5 
June    9 

June  27 
June  28 
June  29 
June  30 

Toulon  harbor 

At  sea,   70  miles 
NNE.  of  Algiers. 

Algiers 

Atsea,  S.  of  Minor- 
ca, lat.  39^*0' N.; 
long.  1°32'  E. . . . 

Toulon  harbor  .... 

....Do 

20'935 

20.961 
20.420 
20.395 

20,927 
20.982 
20.928 
20.955 
20.964 

Do 

....Do 

....Do 

....Do           

....Do 1 

Do 

....Do 

....Do 

38 


Composition  of  the  Atmosphere 


Table  IS.— Analyses  of  air  collected  on  the  Atlantic  Ocean,  between  Liverpool  and 

Vera  Cruz. 


Place. 


At  sea,  lat.  34°  21';  long.  24M0' 

Near  St.  Domingo,  lat.  20°;  long.  72°  30', 


Ent?anS  to' Gulf  of* Mexico',  lat.' 21° '50';  long."  88°'46''. . 
Bay  of  Vera  Cruz ^^^^^^^^^^^^^^^_^^^^^^^^^^^^^ 


Oxygen. 


p.  ct. 
20.922 
20.920 
{  20.920 
\  20.918 
20.962 
20.953 
20.965 


Table  \Q.— Analyses  of  air  collected  at  different  parts  of  the  East  Indian  Ocean. 


Date. 


1848. 
July       5 

Sept.    15 

1849. 

Jan.     15 


Feb. 
Mar. 


Mar.    15 
Mar.    24 


Aug.    25 
Dec.    15 

I860. 

Mar.    19 


Place. 


Bay  of  Goree  (Senegal) 

Lat.33°40'S.;long.  16°15'E. 


Long.  78°  38'  E.;  lat.  2°  29'  S 

Gulf  of  Bengal;  lat.  9°  4'  N.;  long.  83°  E.V 
On  the  Ganges,  near  Calcutta,  noon.^ 


Calcutta 

On  the  Hoogly  River  (East  Indies),  opposite  Ked- 
gerre,  lat.  21°  53'  N 


Mayotte,  off  Mozambique 

Simons  Bay  (Cape  of  Good  Hope) 


Mers-el-K6bir  (coast  of  Africa) 


Oxygen. 


p.  ct. 
20.896 
20.843 
20.854 

20.975 
20.460 
20.453 
20.390 
20.387 
20.866 
20.920 
20.921 
20.928 
20.910 
20.936 

20.870 


*  The  air  contained  0.057  per  cent  of  carbon  dioxide. 

*  A  note  in  connection  witn  this  sample  says  on  March  8  there  was  a  sudden  invasion  of  cholera  and 
no  samples  were  taken  until  March  15.  The  weather  was  excessively  foggy  during  the  night,  and  the 
fogs  did  not  disappear  during  the  day;  the  air  was  full  of  putrefying  vegetable  and  organic  matter,  and 
there  were  many  dead  bodies  in  the  river.    The  air  contained  0.133  per  cent  of  carbon  dioxide. 

Two  exceptions  to  the  usual  results  appear  in  samples  of  air  taken  in 
Toulon  Harbor  on  May  27  at  8^  30°^  a.  m.,  duplicate  analyses  giving 
20.854  and  20.872  per  cent  of  oxygen,  respectively.  These  numbers  are 
appreciably  less  than  the  minimum  which  was  obtained  in  the  air  of  Paris^ 
but  the  air  collected  on  June  5  at  11  p.  m.  in  the  port  of  Algiers  gave  even 
lower  results,  these  being  20.420  and  20.395  per  cent,  respectively.  The 
author  does  not  question  the  sealing  of  the  tubes,  as  it  was  done  by  a 
person  who  had  had  experience  in  his  own  laboratory. 

In  Ecuador  two  samples  were  taken;  one  which  was  collected  in  the 
village  of  Guallabamba  on  August  3,  1848,  at  8^  IS'"  in  the  morning  gave 
20.960  per  cent;  the  other,  taken  on  the  summit  of  Pichincha — a  mountain 
higher  than  Mont  Blanc— on  May  15,  1849,  at  12^  45°^  p.  m.,  gave  20.949 
and  20.988  per  cent,  respectively. 

Among  the  analyses  of  air  collected  on  the  East  Indian  Ocean  (see 
table  19),  only  two  show  a  composition  very  different  from  that  of  normal 


History  of  Air-Analysis 


39 


air.  The  analysis  of  air  collected  on  February  1,  1849,  in  the  Gulf  of 
Bengal,  gave  20.460  and  20.453  per  cent  of  oxygen.  The  notes  which 
accompany  this  sample  do  not  present  anything  of  distinct  interest.  The 
air  collected  on  the  Ganges  on  March  8, 1849,  shows  20.390  and  20.387  per 
cent  of  oxygen,  and  Regnault  maintains  that  the  conditions  set  forth  in 
the  notes  accompanying  this  sample  explain  this  anomalous  case.  Four 
other  samples  taken  in  1852  at  different  points  in  the  Pacific  and  South 
Atlantic  Ocean  gave  21.015,  20.935,  20.950,  and  20.963  per  cent  of  oxygen, 
respectively.  Samples  of  air  from  the  Arctic  Ocean  were  also  analyzed, 
these  being  given  in  table  20. 

Table  20. — Analyses  of  air  collected  on  the  Arctic  Ocean. 


Date. 

Place. 

North 
latitude. 

East 
longitude. 

Oxygen. 

1848. 

June      1 
June    20 
July       1 
Oct.     15 
Oct.     15 
Nov.    15 

1849. 

Jan.     15 
Mar.      1 
Mar.    15 
Mar.    15 
Apr.     15 
Apr.     15 
May      1 
May      1 
Aug.      1 
Aug.    15 
Aug.    15 

Cape  Farewell 

Whale  Island    

o              / 

60    10 
67      5 
70    20 
73    52 
73    52 
73    52 

73    52 
73    52 
73    52 
73    52 
73    52 
73    52 
73    52 
73    52 
73    52 
73    52 
73    52 

39     14 
55      9 
55    30 
90    12 
90    12 
90    12 

90     12 
90    12 
90    12 
90    12 
90     12 
90    12 
90    12 
90     12 
90     12 
90     12 
90    12 

20.91 
20.91 
20.92 
20.93 
20.93 
20.85 

20.91 
20.89 
20.86 
20.86 
20.90 
20.94 
20.93 
20.91 
20.87 
20.94 
20.94 

Black  Hook 

Port  Leopold          .    . . 

....Do 

....Do 

Port  Leopold 

....Do 

....Do 

....Do 

..Do 

....Do 

....Do 

....Do 

....Do 

....Do 

....Do 

Regnault's  conclusions  are:  (1)  that  the  air  of  our  atmosphere  usually 
presents  variations  in  composition  which  are  sensible  but  very  small,  for 
the  percentage  of  oxygen  varies  generally  only  from  20.9  to  21.0,  although 
in  certain  cases,  apparently  more  frequent  in  the  warm  countries,  the 
proportion  of  oxygen  may  fall  to  20.3  per  cent;  (2)  that  the  average  per- 
centage of  oxygen  contained  in  the  air  of  Paris  during  the  year  1848  was 
20.96. 

The  importance  of  a  geographical  study  of  the  composition  of  the 
atmosphere  was  so  keenly  felt  that  the  French  Academy  commissioned 
Lewy^  to  make  analyses  of  air  while  on  a  voyage  to  South  America. 
The  analyses  were  made  by  the  method  of  Regnault  and  Reiset.  Pre- 
vious to  taking  this  journey,  he  made  several  analyses  of  air  in  France. 
On  September  6,  1847,  Lewy  found  as  a  result  of  three  analyses  of  air  in 
Paris,  21.018,  21.015,  and  21.008  per  cent,  with  an  average  of  21.014  per 
cent.  In  Havre,  he  found  on  November  22,  1847,  that  in  three  analyses 
the  percentages  of  oxygen  were  20.895,  20.880,  and  20.888,  with  an  average 
of  20.888  per  cent. 

^  Lewy,  Annales  de  Chimie  et  de  Physique,  ser.  3, 1852, 34,  p.  5. 


40 


Composition  of  the  Atmosphere 


The  analyses  of  the  atmospheric  air  collected  on  the  Atlantic  Ocean 
and  the  Caribbean  Sea  are  reported  in  table  21,  the  results  giving  an 
average  of  0.046  per  cent  for  carbon  dioxide  and  21.03  per  cent  for  oxy- 
gen. On  examining  his  figures,  Lewy  found  that  the  composition  of  the 
air  collected  during  the  day  differed  from  that  collected  during  the  night, 
the  air  of  the  day  being  richer  in  carbon  dioxide  and  oxygen.  He  accord- 
ingly averaged  his  results  for  both  the  day  and  the  night,  obtaining  the 
following  values:  for  the  day,  carbon  dioxide  0.053  per  cent,  oxygen  21.06 
per  cent;  for  the  night,  carbon  dioxide  0.0346  per  cent,  oxygen  20.97 
per  cent. 

Table  21. Analyses  of  air  collected  on  the  Atlantic  Ocean  and  the  Caribbean  Sea. 


Average  of  3  analyses 

of  each  sample. 

Date. 

Latitude  N. 

Longitude  W. 
from  Paris. 

Carbon 
dioxide. 

Oxygen. 

1847. 

o 

, 

O             ' 

p.ct. 

p.ct. 

Dec.    1 

47 

30 

10      5 

0.0488 

21.05 

Dec.    4 

47 

00 

13      0 

.0334 

20.96 

Dec.    8 

35 

40 

20    35 

.0550 

21.06 

Dec.  17 

22 

5 

39      0 

.0577 

21.06 

Dec.  18 

21 

45 

41      3 

.0335 

20.96 

Dec.  18 

21 

9 

42    25 

.0542 

21.06 

Dec.  19 

20 

35 

43    35 

.0339 

20.96 

Dec.  26 

15 

49 

64    28 

.0529 

21.06 

I      Dec.  28 

14 

6 

70      4 

.0509 

21.06 

Dec.  30 

12 

5 

76      0 

.0514 

21.06 

Dec.  31 

.0377 

21.01 

Lewy  concludes  that  the  difference  between  the  oxygen  and  carbon 
dioxide  in  the  atmospheric  air  on  the  ocean  and  in  normal  air  becomes 
more  noticeable  the  farther  away  one  goes  from  the  land.  He  further 
says  that  it  is  impossible  to  attribute  this  difference  to  errors  in  analysis, 
as  he  maintains  that  two  analyses  of  air  do  not  differ  by  more  than  1  part 
in  10,000.  According  to  his  interpretation  of  the  results,  this  difference  is 
caused  by  the  fact  that  the  water  of  the  ocean  gives  off  carbon  dioxide  and 
oxygen.  During  the  day  the  surface  of  the  sea  becomes  warmed  by  the 
sun's  rays  and  a  part  of  these  gases  is  dissolved;  during  the  night,  on  the 
contrary,  this  influence  is  not  felt. 

Results  of  analyses  of  air  samples  collected  in  New  Granada  on  a  trip 
from  Santa  Marta  to  Montserrat  are  given  in  table  22,  while  the  results 
obtained  from  air  collected  in  1850  in  Bogota,  at  a  height  of  2645  meters, 
with  an  average  barometer  of  565  mm.,  are  reported  in  table  23.  The 
high  values  for  carbon  dioxide  are  attributed  to  the  presence  of  volcanoes 
3  or  4  hours  distant  from  Bogota. 

In  a  general  r4sum6  of  the  subject,  the  author  concludes  that  by  ex- 
amining these  results  (tables  21  to  23),  one  sees  that  the  composition  of  the 
air  up  to  a  height  of  about  3000  meters  is  nearly  the  same  in  the  New 


History  of  Air-Analysis 


41 


World  as  in  the  Old  World,  but  not  absolutely  constant.  The  increase 
in  the  percentage  of  carbon  dioxide,  which  rose  as  high  as  0.49  per  cent — 
14  or  16  times  the  normal  percentage — is  attributed  by  Lewy  to  the  in- 
fluence of  large  forest  fires  and  the  presence  of  volcanoes. 

Table  22.— Analyses  of  air  from  New  Granada. 


Date. 


1848. 

Jan.  25 

Feb.  7 

Feb.  18 

Mar.  3 

Mar.  29 

Aug.  5 

Aug.  2 

Apr.  2 

Aug.  2 

July  8 

July  8 


Place. 


Santa  Marta     . .  , 

Mompox 

Magdalena  River 

....Do 

Honda    

Ambalema 

Esperanza 

Guaduas    

Santa  Ana 

Bogota 

Montserrat    


Elevation. 


meters. 

0 

38 


242 

282 
396 
996 
998 
2645 
3193 


Average  of  3  analyses 
of  each  sample. 


Carbon 
dioxide. 


p.  ct. 

0.046 
.031 
.033 
.046 
.032 
.112 
.245 
.031 
.123 
.050 
.052 


Oxygen. 


p.  ct. 

21.02 

21.05 

21.03 
21.00 
20.99 
20.55 
20.33 
21.00 
20.54 
21.03 
20.99 


Table  23. — Analyses  of  air  from  Bogota  (2645  meters). 


Date. 

Carbon 
dioxide. 

Oxygen. 

Date. 

Carbon 
dioxide. 

Oxygen. 

1850. 

p.ct. 

p.ct. 

1850. 

p.ct. 

p.  ct. 

Mar.    7 

0.0386 

21.02 

Sept.    2 

0.1704 

21.03 

Apr.  12 
May    8 

.0366 

21.00 

Sept.    3 

.1585 

21.02 

.0361 

20.99 

Sept.    3 

.4896 

21.03 

May    9 

.0382 

20.99 

Sept.    3 

.4904 

21.03 

June  15 

.0419 

21.00 

Sept.    4 

.1326 

21.03 

July  24 

.0425 

21.02 

Sept.    4 

.0865 

21.00 

Aug.  19 

.0504 

21.01 

Sept.    8 

.1283 

21.02 

Aug.  23 

.0481 

21.02 

Sept.    9 

.0751 

21.03 

Sept.    1 

.0618 

21.02 

Sept.  10 

.0458 

21.03 

Sept.    2 

.0765 

21.02 

Sept.  12 

.0471 

21.03 

Sept.    2 

.1629 

20.97 

Oct.     3 

.0475 

21.02 

The  hydrogen-explosion  method  and  the  weighing  of  the  amount  of 
oxygen  absorbed  by  a  metal  or  by  phosphorus  involved  an  exceedingly 
elaborate  technique  and  restricted  the  number  of  observations  that  could 
possibly  be  made  by  one  man  in  a  day.  In  1851  there  appeared  the  de- 
scription of  a  method  of  absorbing  oxygen  by  means  of  an  alkaline  solu- 
tion of  pyrogallic  acid.  Liebig^  reported  the  results  of  11  analyses,  with 
percentage  values  as  follows:  20.99,  20.89,  21.03,  20.95,  20.77,  20.92, 
20.90,  20.80,  20.75,  20.76,  20.93.  With  this  method  he  maintained  that 
in  an  hour  half  a  dozen  analyses  could  be  carried  out.  GalHc  acid  could 
also  be  used  instead  of  pyrogaUic  acid,  although,  according  to  Liebig,  the 
absorption  required  a  longer  time  than  with  pyrogallic  acid,  i.e.,  1^  to  2 
hours  instead  of  as  many  minutes.     Liebig  gives  the  results  of  8  analyses 


1  Liebig,  Annalen  der  Chemie  und  Pharmacie,  1851, 77-78,  p.  107. 


42 


Composition  of  the  Atmosphere 


obtained  with  gallic  acid  with  percentages  of  oxygen  as  follows:  20.59, 
20.69,  20.97,  20.52,  21.35,  20.80,  20.78,  and  21.19. 

This  method  was  destined  to  become  one  of  the  most  important  meth- 
ods for  technical  gas-analysis  that  had  ever  been  devised.  It  is  interesting 
to  note  that  at  this  date  (1912)  practically  all  of  the  exact  gas-analysis 
apparatus  employ  the  alkaline  solution  of  pyrogallol.  Almost  imme- 
diately after  the  introduction  of  the  method  it  was  found  that  under 
certain  conditions  the  interaction  of  air  with  pyrogallic  acid  and  potas- 
sium hydroxide  resulted  in  the  formation  of  slight  quantities  of  carbon 
monoxide.  This  for  a  time  discouraged  observers  from  using  the  method. 
Subsequently  conditions  were  so  adjusted  as  to  minimize  this  apparent 
error. 

Using  a  modification  of  the  Regnault  method,  Frankland  and  Ward^ 
published  6  analyses  of  air  as  an  indication  of  the  accuracy  of  the  ap- 
paratus. The  results  given  are  20.880,  20.888,  20.883,  20.867,  20.868, 
and  20.876  per  cent,  with  an  average  of  20.877  per  cent,  the  greatest 
difference  being  only  0.021  per  cent. 

Frankland  in  1861,  ^  reporting  the  results  of  some  air  samples  taken  by 
himself  on  an  excursion  to  the  top  of  Mont  Blanc,  cites  analyses  of  air 
collected  during  a  balloon  ascension  in  August  1852,  which  were  made  by 
Dr.  Miller.  At  a  height  of  18,000  feet  the  oxygen  percentage  was  found 
to  be  20.88;  a  sample  taken  at  the  same  time  at  the  surface  of  the  earth 
gave  20.92  per  cent.^ 

Frankland's  analyses  of  the  air  from  Mont  Blanc  were  made  by  ab- 
sorbing the  carbon  dioxide  by  means  of  caustic  potash,  and  determining 
the  oxygen  by  explosion  with  electrolytically  prepared  hydrogen.  Speci- 
mens were  taken  at  Chamounix  (altitude  3000  feet),  at  the  Grands 
Mulets  (11,000  feet),  and  at  the  top  of  Mont  Blanc  (15,732  feet).  At 
Chamounix  the  percentages  of  oxygen  found  were  20.892  and  20.870,  and 
of  carbon  dioxide,  0.063.  At  the  Grands  Mulets,  two  samples  showed 
20.793  and  20.765  per  cent  of  oxygen  and  0.111  per  cent  of  carbon  dioxide. 
At  the  summit  of  Mont  Blanc,  on  August  21,  at  8^  45™  a.m.,  two  samples 
gave  20.950  and  20.951  per  cent  of  oxygen  respectively,  and  0.061  per  cent 
of  carbon  dioxide.    The  averages  of  all  the  results  are,  therefore,  as  follows : 


PUce. 

Carbon 
dioxide. 

Oxygen. 

Chamounix 

p.  ct. 

0.063 
.111 
.061 

p.ct. 

20.894 
20.802 
20.963 

Grands  Mulets  

Summit  of  Mont  Blanc  . . 

»  Frankland  and  Ward,  Quarterly  Journal  of  the  Chemical  Society,  London,  1854,  6» 
p.  197. 

«  Frankland,  Quarterly  Journal  of  the  Chemical  Society,  London,  1861, 13,  p.  22. 

2  Julius  Hann  in  his  Lehrbuch  der  Meteorologie,  Leipzig,  1901,  p.  9,  states  that  sam- 
ples of  air  were  collected  in  a  balloon  journey  made  by  Welsh;  according  to  the  analyses 
made  by  Miller,  the  oxygen  content  on  the  surface  of  the  earth  was  found  to  be  20.92  per 
cent;  at  4100  meters,  20.89;  at  5500  meters,  20.75 ;  and  at  56.80  meters,  20.89  per  cent. 


History  of  Air-Analysis 


43 


Two  series  of  analyses  of  the  air  of  Madrid  were  made  by  Torres 
Muiioz.i  The  percentages  of  oxygen  are  very  small,  and  those  of  carbon 
dioxide  usually  very  high,  the  latter  ranging  from  0.02  to  0.09  per  cent. 
The  oxygen  was  determined  in  part  by  cuprous  ammonium  chloride  and 
in  part  by  potassium  pyrogallate.  The  percentages  of  oxygen  obtained 
are  given  in  table  24. 

Table  24. — Analyses  of  air  collected  in  Madrid  by  Torres  Munui, 


Oxygen  outside  the  walls,  in  March. 

Oxygen  within  the  walls,  in  AprU. 

V.ct. 

v.ct. 

P.ct. 

v.ct. 

20.71 

20.70 

20.70 

20.78 

20.79 

20.74 

20.70 

20.69 

20.77 

20.69 

20.77 

20.70 

20.77 

20.81 

20.75 

20.78 

20.73 

20.79 

20.70 

20.80 

20.75 

20.78 

20.69 

20.73 

Another  investigator,  Russell,^  using  a  modified  Bunsen  apparatus, 
reports  in  1868  an  analysis  of  air  as  containing  20.845  per  cent  of  oxygen. 

One  of  the  first  to  use  the  pyrogallic-acid  method  for  the  analysis  of 
atmospheric  air  was  Schiel,^  who  in  1857  determined  the  oxygen  content 
of  air  at  an  altitude  of  2330  feet  on  the  boundary  between  Kansas  and 
Colorado,  finding  20.91  per  cent  as  an  average  of  three  experiments. 

The  importance  of  Liebig's  discovery  of  the  use  of  potassium  pyrogal- 
late as  an  absorbing  agent  for  oxygen  was  early  recognized  by  Speck,  ^ 
who  submitted  the  method  to  numerous  tests  in  connection  with  his 
physiological  researches.  Speck  recommends  the  use  of  barium  hydroxide 
in  place  of  potassium  hydroxide  to  prevent  the  formation  of  carbon  mon- 
oxide. The  analyses  with  barium  hydroxide  and  pyrogallic  acid  agreed 
well  with  the  Bunsen  explosion  method.  Duplicate  analyses  by  the 
barium  pyrogallate  method  gave  results  as  follows : 


Date. 

I. 

II. 

1866. 

Sept.  23 
Oct.    10 
Oct.    11 

V.et. 
20.98 
20.93 
20.93 

v.ct. 
20.97 
20.96 
20.98 

One  of  the  most  extensive  investigations  of  the  oxygen  content  of 
atmospheric  air  was  that  carried  out  by  R.  Angus  Smith,  of  Manchester, 

*  Estudios  quimicos  sobre  el  aire  atmosf^rico  de  Madrid,  por  D.  Ramon  Torres 
Munoz  de  Luna,  Madrid,  1860.  A  translation  of  this  entire  paper  was  made  by  de 
Chambry  and  published  in  Annales  d'Hygiene  Publique  et  de  Medicine  legale,  1865, 
series'2,  15,  p.  337. 

*  Russell,  Joum.  Chem.  Soc,  London,  1868,  newser.,  6,  p.  140. 

3  Schiel,  Annalen  der  Chemie  und  Pharmacie,  1857, 103,  p.  120. 

*  Speck,  Sehriften  der  Gesellschaft  zur  Beforderung  der  gesammte  Naturwissenschaft 
zu  Marburg,  1871, 10. 


44 


Composition  of  the  Atmosphere 


England.  His  results,  which  were  first  published  in  a  condensed  form,^ 
were  subsequently  given  more  in  detail  as  a  part  of  a  larger  publication.  * 
Using  for  the  most  part  the  explosion  apparatus  of  Bunsen,  although 
making  several  ineffective  attempts  to  secure  accurate  results  by  means 
of  Liebig's  pyrogallic-acid  method,  Smith  made  an  enormous  number  of 
analyses  of  outdoor  air  in  connection  with  his  investigation  of  the  ven- 
tilation of  houses.  In  his  book,  which  contains  the  best  collection  of  the 
literature  and  analyses  of  outdoor  air  thus  far  published  in  English,  he 
reports  over  100  determinations  of  the  oxygen  content  of  outdoor  air. 
Firmly  impressed  with  the  belief  that  the  presence  of  putrefying  organic 
matter  requires  a  material  draft  upon  the  oxygen  of  the  air.  Smith  made 
a  comparative  study  of  the  air  collected  at  the  front  door  of  the  labora- 
tory and  in  outhouses  in  the  near  neighborhood.  His  results  are  given  in 
table  25. 


Table  25. — Determinations  made  by  Smith  of  oxygen 

in  outdoor  air  and  in  the 

air  of  outhousea 

in  Manchester 

» 

Date. 

Air  from  front 
door  of  labo- 
ratory. 

Air  from 
outhouses. 

i           Date. 

Air  from  front 
door  of  labo- 
ratory. 

Air  from 
outhouses. 

1863. 

p.ct. 

p.ct. 

i          1863. 

p.ct. 

p.ct. 

Dec.     1 

20.90 

20.80 

Dec.  19 

20.87 

Dec.  10 

20.96 

20.85 

!     Dec.  21 

20.92 

20.56 

Dec.  11 

20.98 

20.79 

i     Dec.  21 

21.02 

20.79 

Dec.  11 

20.90 

20.72 

j     Dec.  21 

20.88 

20.64 

Dec.  15 

20.90 

20.87 

Dec.  21 

20.91 

20.94 

Dec.  15 

20.02 

20.76 

Dec.  21 

21.01 

20.67 

Dec.  17 

20.96 

20.59 

Dec.  22 

20.96 

20.53 

Dec.  17 

20.78 

20.85 

Dec.  22 

20.92 

20.71 

Dec.  17 

20.83 

20.90 

1864. 

Dec.  18 

20.91 

20.21 

Feb.  26 

21.01 

20.66 

Dec.  18 

20.92 

20.58 

Feb.  24 

21.05 

.... 

Dec.  18 

20.87 

20.74 

Feb.  20 

20.98 

Dec.  18 

21.02 

20.40 

Feb.  20 

20.99 

Dec.  18 

21.00 

20.77 

Feb.  20 

21.01 

Dec.  19 

20.83 

20.99 

Feb.  20 

20.94 

Dec.  19 

20.98 

20.70 

Dec.  19 

20.88 

20.82 

Average 

20.943 

20.70 

Dec.  19 

21.01 

20.46 

A  very  extensive  examination  of  the  air  of  London  was  carried  out  by 
Smith  in  November  1869.  These  analyses  give  us  a  method  of  judging  of 
the  accuracy  of  Smith's  method  and  the  agreement  of  duplicates.  They 
are  in  part  reported  in  table  26. 

The  probable  influence  of  weather  conditions,  especially  moisture 
and  fog,  led  Smith  to  investigate  the  changes  in  oxygen  content  as  affected 
by  this  factor.  Five  analyses  are  reported  of  air  taken  near  the  labora- 
tory in  Manchester  during  wet  weather,  the  results  being  20.90,  21.01, 
21.01,  21.05,  and  20.96  per  cent  of  oxygen,  respectively,  with  an  average 

>  Smith  Memoirs  of  the  Literary  and  Philosophical  Society  ofjManchester,  1864-65, 
ser.  u,  Of  p.  6. 

*  Smith,  Air  and  rain ;  the  beginnings  of  a  chemical  climatology.    London,  1872. 


History  of  Air-Analysis 


45 


of  20.98  per  cent.     In  dry  and  foggy  weather,  when  the  smoke  of  Man- 
chester hung  over  the  town,  the  results  were  as  follows: 

Oxygen 
percentage. 

Near  center  of  town    j  ^^-^^ 

At  laboratory    j  20-90 

At  laboratory,  afternoon 20.91 

At  laboratory,  forenoon      21.01 

At  laboratory,  afternoon 20.82 

Average 20.91 

Table  26. — Determinations  made  by  Smith  of  oxygen  in  London  air. 


Place. 


j        First 
analysis. 


Islington,  Duncan  Terrace 

Hoxton,  Hoxton  Square 

Dalston,  Albion  Road 

Hackney,  near  Hackney  Station  . 
Clarendon  Square,  Somers  Town 
Alpha  Road  and  Grove  Road    . . 


Average  

Parks  and  open  places. 

Near  Belsize  Park    

Kennington  Park     

Chelsea  Hospital,  gardens  near  river 

Vauxhall  Bridge,  near  river 

Houses  of  Parliament,  terrace  

Hyde  Park,  Sloane  Street 

Middle  of  Hyde  Park   


Average 


p.  ct. 

20.86 
20.85 
20.90 
20.82 
20.90 
20.87 


21.02 
20.96 
20.91 
20.90 
20.96 
20.91 
21.03 


Second 
analysis. 


Average. 


p.  ct. 

20.81 
20.82 
20.91 
20.85 
20.89 
20.80 


21.00 
20.92 
20.91 
20.91 
20.93 
20.94 
20.98 


p.  ct. 

20.835 
20.835 
20.905 
20.835 
20.895 
20.835 

20.857 


21.010 
20.940 
20.910 
20.905 
20.945 
20.925 
21.005 

20.95 


In  a  very  dense  fog,  which  Smith  states  was  a  rare  experience  in  Man- 
chester, and  which  made  the  eyes  smart  and  walking  difficult,  he  found 
20.82  and  20.89  per  cent  of  oxygen.  In  the  yard  back  of  the  laboratory 
he  regularly  found  somewhat  less  oxygen  than  in  the  front,  his  results 
being  20.80,  21.01,  20.94,  20.84,  21.09  per  cent,  respectively,  with  an 
average  of  20.936  per  cent.     He  summarized  his  results  as  follows : 

Oxygen 
percentage. 

In  very  wet  weather,  in  front  of  the  laboratory     20.98 

At  all  times  (average  of  32  experiments)     20.947 

Behind  the  laboratory,  in  medium  weather 20.936 

In  foggy  frost 20.91 

In  outhouses  20.706 

If  we  except  the  air  from  outhouses,  we  find  an  average  variation  in 
these  analyses  of  0.07  per  cent. 

During  1863  to  1865  Smith  made  an  extensive  examination  of  the  air 
at  both  the  summit  and  base  of  a  number  of  mountains  in  Scotland. 
While  the  altitudes  were  by  no  means  as  great  as  those  of  the  Alps,  and 
hence  the  results,  which  are  given  in  table  27,  can  not  contribute  exten- 


46 


Composition  of  the  Atmosphere 


sively  to  the  question  of  the  Dalton  hypothesis,  nevertheless  they  are 
extremely  interesting  as  showing  careful  [attention  to  a  very  important 
problem. 

Table  27. — Determinations  made  by  Smith  of  oxygen  in  the  air  from  mountainous  districts 

of  Scotland. 


Place. 


Ben  Kevis  

Do 

Do 

Do 

•Do 

Lochin-y-gair  (Balmoral) 

Do 

Ben  Ledi 

Do 

Do. 

Beu  Voirlich 

Do 

Ben-na-bourd 

Ben  Lomond 


Summit. 

Base. 

p.ct. 

P^'^^o 

20.91 

20.93 

20.96 

20.91 

20.94 

20.89 

20.88 

.... 

21.01 

.... 

20.94 

20.80 

20.95 

21 

20.98 

21.02 

20.97 

.... 

20.97 

.... 

21.01 

20.87 

20.88 

21.03 

21.18 

20.94 

20.95 

Place. 


Ben  Lomond  . . 

Do 

Ben  Muich  Dhu 

Do 

Do 

Do 

Do 

Do 

OchiU  Hill 

Do 

Moncrieffe  Hill  , 

Average  . , 


Summit. 


p.  ct. 

21.08 
20.91 
21.00 
21.07 
21.02 
20.99 
20.93 
21.01 
21.05 
21.07 
20.93 

20.98 


Base. 


p.ct. 


20.94 


For  comparison,  Smith  analyzed  a  large  number  of  samples  of  air 
from  districts  in  Scotland  with  but  slight,  if  any,  elevation.  (See  table 
28.)  Of  particular  significance  is  the  extremely  low  value  found  near 
Inverness,  which  Smith  attributes  to  some  impurity  arising  from  the 
water. 

Table  28. — Determinations  m,ade  by  Smith  of  oxygen  in  air  from  districts  not  mountainous. 


Place. 


Oxygen.  '  Average. 


Place. 


Oxygen.  Average 


Shore  at  Lossiemouth .... 

Do 

Inverness,  at  Moray  Frith 

Do : 

Do 

Inverness,    behind    the 

town^ 

Sea-shore.  Oban  

Edinburgh,  Prince's  street 

Do 

Edinburgh,  Calton  Hill. . . 
Aboyne    

Do 

Do : 

Aberdeen,  sea-shore* 

Do 

Do 


p.ct. 

p.ct. 

21.05 

20.95 

21.66 

20.89 

20.89 

20.86 

20.88  1 

20.88 

.... 

20.98 

.... 

20.99 

.... 

20.92 



20.94 
20.94 
20.95 
21.02 
21.05 
21.01 
21.07 


20.95 
20.96 
2i'64 


Errol,  marshy  ground^ 

Do 

Caledonian  Canal  (near 

Inverness)* 

Balmoral 

Do 

Taynuilt  (near  Oban) . . 

Do 

Braemar-on-the-Dee^  . . 

Huntly 

Mar  Forest^ 

Do 

Do 

Do 

Forest  near  Braemar  . . 


Total  average  . . . 


p.  ct. 

20.91 
20.96 

20.88 
20.88 
21.00 
20.92 
20.86 
21.18 
21.03 
21.04 
21.02 
21.08 
20.88 
20.87 


p.ct. 

20.94 

2b*.96 
20.89 


21.00 


20.96 


'  ^Py^'^}^^  weather.  =»  Windy  and  cloudy. 

Wmd  from  sea,  N.;  evening.      ♦  Cloudy  and  windy,  SW. 


'  Cloudy. 

^  Rain  and  sunshine. 


Although  unquestionably  slightly  affected  by  the  carbon  dioxide  in 
the  exhalations  of  the  inhabitants  and  in  the  production  of  furnaces  and 
stoves  in  Perth,  the  results  of  Smith's  analyses  of  air  collected  from  a 


History  of  Air-Analysis 


47 


number  of  alleys  and  narrow  streets  in  this  city  are  also  given  here  (see 
table  29). 

Table  29. — Determinations  made  by  Smith  of  oxygen  in  air  from  the  worst  places  in  Perth.^ 


Place. 

Oxygen. 

Place. 

Oxygen. 

Close,  70  South  street 

Close,  44  Pomarium 

p.ct. 
20.87 

20.92 
20.94 
20.93 
20.96 
20.94 
20.96 
20.99 
20.94 

Long  Close,  off  George  street. . 

Close,  28  Watergate    

Close,  82  South  street 

Hewat's  Close,  148  South  st. . . 
Do 

p.ct. 
-    20.90 
21.02 
•  21.01 
20.97 
21.00 
20.90 

20.95 

Do 

Do 

Weaver's  Close,  Pomarium. . . 
Do  . .               

Close,  44  Meal  Vennel    

Average 

St  Paul's  Close 

Do 

Long  Close,  o£f  George  street 

*  Results  of  determinations  made  on  air  which  was  obviously  indoor  have  been  omitted. 

The  results  found  by  Smith  in  Scotland  in  1863-5  are  summarized  by 
him  as  follows: 

Av.  p.  ct. 
of  oxygen. 

Sea-shore  and  heath    20.999 

Summit  of  hills 20.98 

Base  of  hills    20.94 

Places  not  mountainous    20.978 

Inferior  parts  of  town  (favorable,  i.e.,  windy  weather)  20.95 

Lower  places,  marshy,  etc 20.922 

Forests     20.97 


Total  average 20.96 

During  a  visit  to  Switzerland  in  August  1864,  Smith  collected  a  num- 
ber of  samples  of  air  and  determined  the  oxygen.  In  giving  the  results, 
he  includes  for  comparison  a  series  of  four  analyses  of  air  taken  in  the 
following  month  among  some  brushwood  at  Reddish,  near  Manchester. 
(See  table  30.) 

Table  30. — Determinations  made  by  Smith  of  oxygen  in  air  from  marshy  or  confined 

places,  Switzerland. 


Place. 


Sion,  upper  valley  of 
the  Rhone,  Switzer- 
land, over  water  and 
marshy  grass  (morn- 
ing)   


Sion,  over  water  and 
brushwood  (morning) 


Oxygen.    Average. 


p.  ct. 


20.86 

'21.011 

20.94 

21.05 

21.02 

20.96 

20.94 

20.95 

20.83 

21.00 

20.90J 


p.  ct. 


20.95 


Place. 


Lauterbrunnen , 


Chamounix,  Montanvert 
Verdin,  in  the  Sologne  . . 
Vouzerou    


Reddish,  near  Manches- 
ter, England,  among 
brushwood 


Oxygen.     Average. 


p.  ct. 
(  20.94 
]  20.97 
( 20.95 
21.03 
20.99 
\  20.97 
I  20.90 
^21.01 
I  20.90 
r20.92 
)  20.98 
)  20.95 
120.90 


p.  ct. 

20.953 

21.01 
20.95 


20.937 


48 


Composition  of  the  Atmosphere 


Again,  in  the  winter  of  1869  a  large  number  of  analyses  were  made  of 
air  collected  in  both  the  congested  portions  and  the  open  parts  of  the  city 
of  Glasgow.     The  results  are  given  in  table  31. 

Table  31. — Determinations  made  by  Smith  of  oxygen  in  air  from  Glasgow. 


Place. 

Oxygen. 

First 
analysis. 

Second 
analysis. 

Average. 

Congested  sections. 

Buchanan  street,  near  Western  Club 

Exchange,  front  of 

p.ct. 

20.92 
20.89 
20.88 
20.90 
20.96 
20.92 
20.90 
20.90 

20.88 
20.87 
20.86 
20.88 
20.88 
20.85 
20.87 

p.ct. 

20.91 
20.90 
20.88 
20.93 
20.90 
20.91 
20.85 
20.88 

20.87 
20.86 
20.88 
20.87 
20.88 
20.90 
20.89 

p.ct. 

20.915 
20.895 
20.880 
20.915 
20.930 
20.915 
20.875 
20.890 

20.875 
20.865 
2(T.870 
20.875 
20.880 
20.875 
20.880 

Union  .street    

Miller  street,  Argyle  street 

Argyle  street,  near  Queen  street 

St.  Enoch's  Square    

Cross    

Blackhoy  Close,  GaIlo'.vgate    

Gallowgate,  between  Kent  street  and  bar- 
racks  

A  close,  High  street 

Armour  street,  near  barracks 

Kirk  street 

Coulter's  lane,  Abercromby  street    

A  small  court,  Tobago  street     

Oswald  street,  Dalmarnock  road 

Average 

20.90 
20.92 
20.94 
20.92 
20.93 
20.91 
20.94 
20.90 
20.95 
20.88 
20.95 
20.90 
20.98 
20.90 
20.98 

20.93 
20.92 
20.95 
20.87 
20.91 
20.92 
20.95 
20.92 
20.99 
20.92 
20.90 
20.90 
20.97 
20.92 
21.01 

20.8890 

20.915 
20.920 
20.945 
20.895 
20.920 
20.915 
20.945 
20.910 
20.970 
20.900 
20.925 
20.900 
20.975 
20.910 
20.995 

Open  sections. 
Tennant  street,  St.  Rollox 

Charles  street 

Middleton  place 

Castle  street,  near  the  cathedral . . 

Dobbies  Loan,  near  poorhouse  ...    . 

New  City  road,  near  Abercorn  street 

Ely thswood  Square 

Renfrew  street    

Newton  Terrace,  Sauchiehall  street   

University,  Gilmour  Hill 

Quay,  near  Broomielaw  Bridge 

Anderston  quay . .    . . 

Sharpe's  lane,  Stobcross  street    . 

Finnieston  quay 

Pointhouse  pier 

.  . . 

Average   

20.9293 
20.9092 

Total  average  

' 

Smith  also  cites  two  analyses  made  of  air  collected  by  a  friend  in  the 
West  Indies.^  In  one  taken  on  the  North  Atlantic,  latitude  43°  5'  N., 
longitude,  17°  12' W.,  at  a  point  18  feet  above  water,  at  2^  30™  p.  m.  on  a 
fine  day,  he  found  21.01,  21,  and  20.97  per  cent  of  oxygen,  respectively, 
the  average  being  20.99  per  cent.  In  a  sample  taken  at  St.  John's,  An- 
tigua, on  April  11,  1865,  at  9  a.  m.  on  a  showerv  morning,  three  analyses 
of  the  same  sample  gave  20.96,  20.91,  and  21  per  cent,  with  an  average  of 
20.95  per  cent.  Smith  considers  the  difference  between  these  two  analy- 
ses as  significant,  and  discusses  the  possibility  of  an  influence  on  races, 


History  of  Air-Analysis 


49 


and  sections  of  the  same  race,  of  small  variations  in  the  amount  of  oxygen 
in  the  atmosphere. 

Finally,  Smith  distinguishes  between  pure  and  impure  air  (such  as 
that  collected  in  outhouses)  and  maintains  that  pure  air  deviates  from 
21  by  0.065  per  cent. 

Hinman,!  using  an  explosion  apparatus,  made  analyses  of  air  freed 
from  carbon  dioxide,  obtaining  on  April  25,  1874,  20.94  and  20.93  per  cent 
of  oxygen,  and  on  April  26,  1874,  20.94  and  20.92  per  cent  of  oxygen, 
respectively. 

Using  Bunsen's  method,  A.  R.  Leeds^  analyzed  many  samples  of  air 
collected  in  July,  August,  and  September  of  1876,  near  Hoboken,  New 
Jersey,  at  the  Centennial  Exposition  in  Philadelphia,  and  at  several 
places  in  the  Adirondack  Mountains.     His  results  are  given  in  table  32. 


Table  32. — Determinations  of  oxygen  made  by  Leeds  in  samples  of  outdoor  air. 

Date. 

Location. 

Oxygen. 

Date. 

Location. 

Oxygen. 

1876. 
July     4 
Aug.     2 

Aug.  11 

Aug.  29 
Aug.  30 
Aug.  31 

Sept.    1 

Stevens  Institute . . 
....Do 

....Do 1 

....Do 

....Do 

....Do.. 

....Do 1 

P.ct. 

20.957 
20.957 
20.821 
20.843 
20.954 
20.934 
20.942 
20.952 
20.957 

1876. 

Sept.    7 

Aug.  15 
Aug.  18 
Sept.  26 
July   17 

July  21 

Stevens  Institute  \ 

Centennial  grounds 

..  ..Do 

Stevens  Institute . . 
Keene  Flats,  Adi- 

rondacks 

Mount    M  a  r  c  y  J 

(summit).           ) 

p.ct. 
20.932 

20.944 
20.962 
20.918 
20.915 

21.029 
20.928 
20.926 

In  testing  a  gas-analysis  apparatus,  using  copper  immersed  in  an 
ammoniacal  solution  of  ammonium  chloride  to  absorb  oxygen,  Schlosing^ 
found  20.80  and  20.96  per  cent  oxygen  in  two  samples. 

In  the  decade  between  1879  and  1889  an  unusually  large  number  of 
researches  on  the  composition  of  the  air  appeared,  each  of  far-reaching 
importance.  Prominent  among  these  are  the  papers  of  von  Jolly,  Morley, 
Kreusler,  Vogler,  and  Hempel. 

No  paper  since  that  of  Regnault  stimulated  so  much  subsequent  re- 
search on  the  composition  of  the  air  as  did  the  publication  of  von  Jolly's^ 
investigation.  Working  with  extreme  care  in  an  attempt  to  weigh  the 
gases  in  atmospheric  air,  he  found  in  1876  changes  in  oxygen  content 
amounting  to  0.5  per  cent.  Placing  in  the  bulb  of  an  air  thermometer  a 
copper  spiral  which  could  be  heated  by  an  electric  current  to  incandes- 
cence, von  Jolly  was  able  to  absorb  the  oxygen  by  the  heated  copper 
and  thus  determine  the  percentage  of  oxygen.  His  apparatus  was  ex- 
tremely ingenious  and  also  very  complicated.  His  results  are  given  in 
table  33. 

1  Hinman,  American  Journal  of  Science,  1874  (3),  8,  p.  188. 

2  Leeds,  Annals  Lyceum  of  Natural  History,  New  York,  1878,  p.  193. 

3  Schlosing,  Chemisches  Centralblatt,  1869,  p.  678. 

*  von  Jolly,  Wiedemanns  Annalen,  N.F.,  1879,  6,  p.  520. 


50  Composition  of  the  Atmosphere 

Table  33.— Determinations  of  oxygen  made  by  von  Jolly. 


Date. 

Barometer. 

Wind. 

Oxygen. 

Date. 

Barometer. 

Wind. 

Oxygen. 

1877. 

June  13 
June  18 
June  24 
June  27 
June  31 
July     3 
July  17 
July   19 
July  27 
Oct.   12 
Oct.   14 
Oct.   15 
Oct.   16 

mm. 
714.03 
717.7 
716.8 
718.7 
718.1 
716.9 
713.1 
713.9 
719.9 
715.7 
720.9 
719.3 
723.3 

w. 

N. 

NE. 

NE. 

NE. 

E. 

S. 

sw. 

NE. 

E. 

NW. 

E. 

E. 

p.ct. 
20.53 
20.95 
20.73 
20.65 
20.69 
20.66 
20.64 
20.56 
20.75 
20.78 
20.86 
20.83 
20.75 

1877. 

Oct.  21 
Oct.  23 
Oct.  27 
Oct.  31 
Nov.    2 
Nov.  10 
Nov.  13 
Nov.  20 

Min. 
Max. 
Av... 

mm. 

723.0 
710.6 
721.5 
714.2 
724.1 
718.2 
707.0 
708.9 

E. 
NW. 

N. 
W. 

NE. 
SE. 
W. 

NW. 

W. 

N. 

p.ct. 
20.84 
20.84 
21.01 
20.85 
20.91 
20.56 
20.67 
20.65 

714.03 
721.5 

20.53 
21.01 
20.75 

Since  these  results  agree  with  the  variations  found  earlier  by  him,  von 
Jolly  concludes  that  the  highest  oxygen  percentage  is  accompanied  by  a 
polar  wind.  He  opposes  Regnault's  contention  of  an  approxjmately 
constant  composition  of  the  air  and  in  conclusion  makes  the  following 
interesting  and  important  statements : 

Ob  von  Jahr  zu  Jahr  die  Schwankungen  stets  in  gleichen  Grenzen  erfolgen,  und  ob  im 
Mittel  der  Sauerstoffgehalt  in  jedem  Jahre  der  gleiche  ist,  wird  erst  durch  eine  ausge- 
dehntere  Beobachtungsreihe  sich  feststellen  lassen.  Zunachst  istes  wahrscheinlich, 
dass  ebenso  wie  die  Dauer  der  Polar — und  Aequatorstrome  an  gleichem  Orte  nicht  jedes 
Jahr  die  gleiche  ist,  auch  kleine  Differenzen  im  mittleren  Sauerstoffgehalte  sich  von  Jahr 
zu  Jahr  werden  geltend  machen.  Auch  wird  man  aus  den  Beobachtungen  zweier  Jahre 
schliessen  diirfen,  dass  trotz  der  reicheren  Vegetationsdecke  siidlicherer  Breitegrade  die 
Oxydationsprozesse  (vielleicht  in  Folge  der  hoheren  Temperatur)  die  Reduktionsprozesse 
iibenviegen,  wahrend  umgekehrt  der  reichere  Gehalt  an  Sauerstoff  der  Polarstrome  ein 
Zuriicktreten  der  Oxydationsprozesse  gegen  die  der  Reduktion  fiir  die  nordlicheren  Ge- 
genden  ausdriickt. 

A  series  of  analyses  of  air  samples  taken  at  the  observatory  in  Palermo 
in  1879  were  reported  by  Macagno/  who  was  one  of  the  first  observers  to 
use  potassium  pyrogallate  systematically  in  air-analysis.     (See  table  34.) 


Table  34 

— Results  of  analyses  of 

atm/)spheric  air  made  by  Macagno. 

Date. 

Oxygen. 

Carbon 
dioxide. 

Date. 

Oxygen. 

Carbon 
dioxide. 

1879. 

p.ct. 

p.ct. 

1879. 

p.ct. 

p.ct. 

Feb.  20 

20.879 

0.021 

May  31 

20.017 

0.033 

Feb.  28 

20.891 

.048 

June  10 

20.894 

.041 

Mar.  10 

20.715 

.025 

June  20 

20.918             .043       ! 

Mar.  20 

19.994 

.025      1 

June  30 

20.915 

.043 

Mar.  31 

20.888 

.022      1 

July  10 

20.977 

.020 

Apr.  10 

20.910 

.021 

July  20 

20.984 

.076 

Apr.  20 

20.880 

.064 

July  31 

20.899 

.039 

Apr.  30 

20.898 

.045      1 

Aug.  10 

20.910 

.028 

May  10 

20.913 

.005 

Aug.  20 

20.888 

.030 

1      May  20 

20.902 

.049 

Aug.  31 

20.895 

.039 

1  Macagno,  Chemical  News,  1880,  41,  p.  97. 


History  of  Air-Analysis 


51 


Average  results  for  February,  March,  April,  and  May  (with  rainfall) 
were  for  oxygen,  20.717  per  cent,  and  for  carbon  dioxide,  0.033  per  cent. 
For  June,  July,  and  August  (without  rainfall)  the  average  results  were  for 
oxygen,  20.920  per  cent,  and  for  carbon  dioxide,  0.039  per  cent. 

Macagno  emphasizes  the  low  percentage  of  oxygen  found  during  the 
sirocco  wind,  the  extremely  low  percentages  on  March  20  and  May  31 
being  due  to  this  cause.  The  percentages  of  oxygen  obtained  during  the 
sirocco  were  as  follows : 


1879.  per  cent 

March  20 19.994 

March  21 20.008 

March  22 20.064 

April    15 19.998 


1879.  per  cent 

May  29 20.021 

May  30 20.032 

May  31 20.017 


Commenting  on  these  results,  Macagno  writes  : 

Here  we  have  seven  determinations  of  the  most  important  element  of  air  during  that 
singular  wind  with  its  heat  and  dryness,*  rendering  so  troublesome  the  medium  in  which 
we  are  alwajrs  bathed,  and  in  all  cases  the  want  of  oxygen  is  very  evident. 

Simultaneously,  but  independently  of  von  Jolly,  E.  W.  Morley,^  of 
Cleveland,  engaged  in  the  accurate  analysis  of  air  with  a  view  to  study- 
ing the  variations  in  composition  and  formulating  a  hypothesis  which  he 
hoped  would  be  subsequently  verified  with  an  improved  apparatus. 
Morley  maintained  that  the  descent  of  cold  air  from  higher  regions  brought 
with  it  air  poorer  in  oxygen,  presupposing  the  correctness  of  the  Dalton 
hypothesis.     The  apparatus^  used  was  a  modification  of  that  of  Frank- 

Table  35. — Determinations  of  oxygen  in  atmospheric  air  collected  by  Morley  after  sudden 

depressions  of  temperature. 


Oxygen. 

Oxygen.              | 

Average 

Average 

Date. 

tempera- 

Date. 

tempera- 

ture. 

First 

Second 

Xxae. 

First 

Second 

analysis. 

analysis. 

analysis. 

analysis. 

1878. 

°F. 

p.ct. 

p.ct. 

1879. 

QF. 

p.ct. 

p.ct. 

Dec.  28 

20.98 

20.96 

Feb.  16 

26.3 

20.95 

1879 

Feb.  20 

18.9 

20.87 

20.87 

Jan.     2 

7.6 

20.91 

20.92 

Feb.  26 

22.3 

20.45 

20.50 

Jan.     2 

7.6 

20.90 

20.89 

Feb.  27 

12.8 

20.77 

20.80 

Jan.     3 

-7.2 

20.90 

20.91 

Mar.  15 

22.8 

20.88 

20.84 

Jan.     3 

-7.2 

20.96 

20.97 

Mar.  15 

22.8 

20.84 

20.86 

Jan.     6 

13.5 

20.97 

Mar.  16 

25.3 

20.92 

20.92 

Jan.   10 

9.6 

20.96 

Mar.  17 

24.5 

20.89 

20.90 

Jan.  28 

37.4 

20.96 

Apr.     3 

25.0 

20.77 

20.79 

Feb.     1 

18.5 

20.96 

Apr.     3 

. 

20.85 

20.87 

Feb.     1 

18.5 

20.94 

20.94 

Apr.     4 

27.1 

20.80 

20.80 

Feb.     2 

19.8 

20.91 

20.93 

Apr.     4 

27.1 

20.88 

20.85 

Feb.     2 

19.8 

20.82 

20.80 

Apr.     5 

28.2 

20.77 

20.77 

Feb.  16 

11.1 

20.88 

20.86 

Apr.     5 

28.2 

20.86 

20.82 

» During  the  sirocco  wind  the  relative  humidity  of  air  (determined  by  the  psychrom- 
eter)  is  diminished  to  30°,  24°,  20°,  and  even  18°. 

2  Morley,  American  Journal  of  Science  and  Arts,  1879,  18,  p.  168. 

3  Morley,  loc.  cit.;  also  Amer.  Chem.  Journ.,  1881, 3,  p.  1. 


52 


Composition  of  the  Atmosphere 


land  and  Ward/  in  which  the  hydrogen-explosion  method  is  employed. 
Most  of  the  samples  were  analyzed  in  duplicate,  the  difference  at  times 
being  0.05  per  cent.     An  abstract  of  his  results  is  given  in  table  35. 

The  most  noteworthy  observations  in  this  series  are  the  extremely  low 
values  occasionally  found  for  oxygen.     On  this  point  Morley  says  : 

On  Sept.  16,  1878,  two  very  careful  analyses  of  the  same  sample  gave  20.49  and  20.46 
per  cent  of  oxygen.  *  *  *  Within  the  time  covered  by  the  analyses  now  published, 
there  were  several  well-marked  great  and  sudden  depressions  of  temperature,  and  the  fig- 
ures show  the  falling  off  in  the  proportion  of  oxygen  in  the  air  at  these  times  to  be  as  well 
marked  as  the  depression  of  temperature.  The  deficiency  is  not  proportionate  to  the  de- 
pression of  temperature;  this  could  not  be  expected. 

In  a  second  communication,  ^  Morley  reports  a  very  large  number  of 
analyses  made  with  even  greater  care,  comparing  the  results  with  the 
meteorological  conditions  which  existed  at  the  time.  The  investigation 
extended  from  January  1,  1880,  to  April  20,  1881,  analyses  being  made 
nearly  every  day  except  during  the  vacation  months  of  July,  August,  and 
September  1880.  Usually  duplicate  analyses  of  the  same  sample  were 
made  and  occasionally  several  samples  were  taken  on  the  same  day.  For 
painstaking  care  and  extent  the  work  is  marvelously  complete.  A  part 
of  his  results  are  given  in  table  36,  these  being  fairly  indicative  of  the  ac- 
curacy of  the  work,  and  the  agreement  of  duplicate  analyses. 

Table  36. — Determinations  of  oxygen  in  atmospheric  air  made  by  Morley. 


Date. 

Oxygen. 

Date. 

Oxygen. 

Date. 

Oxygen. 

i 

First 

Second     ! 

First 

Second 

First 

Second 

analysis. 

nnalysis. 

analysis. 

analysis. 

analysis. 

analysis. 

1881. 

p.ct. 

p.ct. 

1%1. 

p.ct. 

p.ct. 

18S1. 

p.ct. 

p.ct. 

Jan.    1 

20.949 

20.939 

Jan. 10 

20.966 

20.967 

Jan.  21 

20.948 

20.950 

Jan.    1 

20.936 

20.940  . 

Jan. 11 

20.957 

20.959 

Jan.  22 

20.938 

20.933 

Jan.    2 

20.954 

20.960 

Jan. 12 

20.963 

20.956 

i  Jan.  23 

20.955 

20.947 

Jan.    2 

20.952 

20.947 

Jan. 13 

20.958 

20.957 

i  Jan.  24 

20.959 

20.958 

Jan.    3 

20.959 

20.957 

Jan. 14 

20.957 

20.961 

Jan.  25 

20.952 

20.947 

Jan.    4 

20.954 

20.951  ! 

Jan. 15 

20.960 

20.961 

Jan.  26 

20.969 

20.967 

Jan.    5 

20.958 

20.958 

Jan. 16 

20.952 

20.952 

Jan.  27 

20.959 

20.959 

Jan.    6 

20.956 

20.953 

Jan.  17 

20.959 

20.957 

Jan.  28 

20.953 

20.961 

1  Jan.    7 

20.958 

20.948 

Jan.  18 

20.950 

20.952 

Jan.  29 

20.960 

20.954 

Jan.    8 

20.946 

20.960 

Jan.  19 

20.956 

20.956 

Jan.  30 

20.968 

20.964 

Jan.    9 

1 

20.954 

20.962 

Jan.  20 

20.958 

20.960 

Jan.  31 

20.960 

20.962 

While  Professor  Morley  cites  numerous  instances  of  meteorological 
conditions  accompanied  by  decreases  in  oxygen  which  are  consistent  with 
his  hypothesis,  there  are  fully  as  many  days  of  low  oxygen  when  he  ad- 
mittedly is  unable  to  explain  the  fall  as  a  result  of  meteorological  change. 
Furthermore,  he  repeatedly  cites  falls  in  oxygen  amounting  to  but  0.01 
per  cent  as  significant.  Morley  concludes  that  there  is  no  connection 
between  the  deficiencies  in  oxygen  and  the  direction  of  the  wind  at  the 


1  Frankland  and  Ward,  Quart.  Journ.  Chem.  8oc.  (London),  1854,  6,  p.  197. 

2  Morley,  American  Journal  of  Science,  1881  (3),  22,  p.  417. 


HiSTOEY  OF  Air-Analysis 


53 


time  of  taking  the  sample  and  ''that  the  theory  that  deficiencies  in  the 
amount  of  oxygen  in  the  atmosphere  are  caused  by  the  descent  of  air  from 
an  elevation  fairly  well  agrees  with  the  facts."  In  another  paper ^  Mor- 
ley  discusses  in  detail  the  improbability  of  the  von  Jolly  hypothesis. 

The  experimental  researches  of  Morley  and  von  Jolly  stimulated, 
among  other  writers,  Vogler,^  who,  in  a  theoretical  presentation  of  the 
subject,  maintains  that  neither  von  Jolly's  hypothesis  nor  that  of  Mor- 
ley explains  the  anomalies  as  well  as  does  the  conception  of  a  separation 
of  the  gases  of  the  air  under  conditions  of  high  pressure.  During  a  period 
of  minimum  barometer  he  maintains  that  the  rapidly  moving  currents  of 
air  thoroughly  mix  the  atmosphere,  so  that  there  is  no  difference  in  the 
oxygen  content,  but  when  there  is  a  period  of  high  barometer  the  air  is 
quiet  and  there  is  a  separation  of  the  gases,  with  a  high  oxygen  content 
near  the  earth. 

Table  37. — Determinations  of  oxygen  made  in  air  analyzed  by  Kreusler. 


Date. 

Oxygen. 

Date. 

Cxygen. 

Date. 

Oxygen.  ' 

Date. 

Oxygen. 

1883.    ! 

p.  ct. 

1883. 

1 

v.ct.     ! 

1883. 

p.  ct. 

1883. 

V.ct. 

Jan.  5 

20.882 

Apr.  2  1 

20.925 

July  12 

20.927 

Oct.  30 

20.879 

Jan.  7 

20.905 

Apr.  5  1 

20.881 

July  18 

20.900 

Nov.  2 

20.899 

Jan.  8 

20.927 

Apr.  9 

20.991 

July  25 

20.924  ! 

Nov.  5 

20.888 

Jan.  9 

20.914 

Apr.  19 

20.867 

July  30 

20.945 

i  Nov.  8 

20.922 

Jan.  11 

20.899 

Apr.  23 

20.923 

Aug.  4 

20.930 

Nov.  12 

20.895 

Jan.  13 

20.925 

Apr.  26 

20.909 

Aug.  7 

20.936 

Nov.  15 

20.909 

Jan.  14 

20.900 

Apr.  30 

20.873 

Aug.  10 

20.906 

Nov.  19 

20.908 

Jan.  17 

20.900 

May  3 

20.896 

Aug.  13 

20.895 

i  Nov.  22 

20.903 

Jan.  20 

20.886 

May  7 

20.909 

Aug.  17 

20.934 

i  Nov.  26 

20.918 

Jan.  21 

20.917 

May  10 

20.919 

Aug.  20 

20.910 

Nov.  29 

20.901 

Jan.  22 

20.902 

May  13 

20.912 

Aug.  24 

20.933 

Dec.  3 

20.876 

Jan.  23 

20.884 

May  16 

20.896 

Aug.  29 

20.917 

Dec.  6 

20.900 

Jan.  25 

20.913 

May  21 

20.928 

Sept.  2 

20.886 

1  Dec.  10 

20.916 

Jan.  26 

20.915 

May  24 

20.914 

Sept.  10 

20.937 

I  Dec.  13 

20.904 

Jan.  27 

20.912 

May  29 

20.906 

Sept.  14 

20.883 

;  Dec.  17 

20.936 

Jan.  28 

20.984 

June  1 

20.927 

j  Sept.  17 

20.923 

Dec.  20 

20.902 

Jan.  29 

20.895 

June  4 

20.918 

!  Sept.  20 

20.888 

Dec.  24 

20.911 

Jan.  30 

20.914 

June  7 

20.926 

!  Sept.  24 

20.890 

Dec.  27 

20.907 

Jan.  31 

20.908 

June  12 

20.937 

i  Sept.  27 

20.985 

1884 

Feb.  4 

20.926 

June  15 

20.917 

Oct.   1 

20.911 

Jan.  11 

20.937 

Feb.  7 

20.937 

June  18 

20.911 

Oct.  4 

20.916 

Jan.  19 

20.922 

Feb.  10 

20.900 

June  20 

20.894 

Oct.  7 

20.885 

i  Jan.  23 

20.941 

Feb.  13 

20.909 

June  25 

20.894 

Oct.  11 

20.924 

Jan.  24 

20.914 

Feb.  16 

20.899 

June  28 

20.926 

Oct.  15 

20.928 

Jan.  27 

20.925 

Feb.  19 

20.911 

July  3 

20.906 

Oct.  18 

20.921 

Jan.  30 

20.925 

Feb.  22 

'    20.895 

July  6 

20.918 

Oct.  22 

20.900 

Feb.  7 

20.936 

Mar.  24 

!  20.884 

July  9 

20.904 

!  Oct.  25 

20.916 

! 

By  far  the  most  complete  collection  of  the  literature  on  the  composi- 
tion of  atmospheric  air  thus  far  published  is  to  be  found  in  the  admirable 
article  by  Kreusler.^     Using  a  eudiometer  similar  to  that  employed  by 

^  Morley,  American  Journal  of  Science,  1881  (3),  22,  p.  429. 

2  Vogler,  Chemisches  Centralblatt,  1882  (3),  13,  p.  556 

3  Kreusler,  Landwirtschaftliches  Jahrbucher,  1885,  14,  pp.  30o-378.  This  article, 
although  published  in  a  somewhat  inaccessible  place,  has  been  most  helpful  in  preparing 
the  material  for  this  memoir.  I  have  freely  drawn  upon  the  matenal  Professor  Kreusler 
has  collected  and  wish  to  express  here  my  appreciation  of  his  paper. 


54  Composition  of  the  Atmosphere 

von  Jolly,  Kreusler  made  a  series  of  analyses  of  atmospheric  air  in  Bonn. 
These  observations  covered  the  whole  year,  averaging  about  8  or  9  ex- 
periments each  month,  March  excepted.  About  the  middle  of  the  year, 
certain  improvements  were  made  in  the  apparatus.  His  results  are  ab- 
stracted in  table  37. 

As  a  result  of  his  experiments,  Kreusler  found  that  the  oxygen  varied 
from  20.867  to  20.991  per  cent  as  the  extreme  limits,  but  with  certain  ex- 
ceptional cases  eliminated,  the  variations  were  from  20.88  to  20.94  per 
cent.  The  99  observations  in  the  year  1883  gave  an  average  result  of 
20.911  per  cent.     The  average  values  for  each  month  were  as  follows: 


January 20.910 

February 20.911 

March 

April 20.910 


May 20.910 

June 20.917 

July 20.918 

August    20.920 


September 20.913 

October 20.909 

November 20.905 

December 20.906 


The  shghtly  higher  values  found  during  the  warmer  months  are  ex- 
plained by  Kreusler  as  being  due  to  the  assimilative  activity  of  vegetation. 

In  referring  to  earlier  analyses,  Kreusler  considers  all  experiments  in 
which  the  variations  were  under  0.1  per  cent  as  normal  results,  those  be- 
tween 0.1  and  0.15  abnormal,  and  those  over  0.15  per  cent  as  most  ab- 
normal. Of  the  1025  observations  that  he  has  been  able  to  find  in  the 
literature  which  are  comparable,  but  15  can  be  classified  under  the  head 
of  ''abnormal"  and  22  under  the  head  of  "most  abnormal."  The  ob- 
servations of  von  Jolly  in  Munich  in  1878  play  an  important  role  in  this 
subdivision,  for  his  results  give  12  normal,  3  abnormal,  and  6  most  abnor- 
mal; Kreusler  points  out  that  while  in  the  case  of  the  other  observations 
97.2  per  cent  are  normal  and  only  1.2  and  1.6  are  abnormal  and  most  ab- 
normal, respectively,  the  experiments  of  von  Jolly  give  but  57  per  cent 
normal,  with  14.3  and  28.6  per  cent,  respectively,  as  abnormal  and  most 
abnormal.  Obviously,  therefore,  von  Jolly  has  found  much  greater  vari- 
ations than  all  the  other  observers  combined,  and  consequently  Kreus- 
ler takes  exceptions  to  his  conclusions.  Furthermore,  the  average  oxy- 
gen content  found  in  von  Jolly's  experiments  was  20.75  per  cent,  which  is 
very  much  lower  than  both  the  earlier  and  later  observations. 

After  considering  the  errors  in  von  Jolly's  experiments,  Kreusler  dis- 
cusses the  anomalous  observations  of  Brunner,  Lewy,  Regnault  and  Lewy, 
Liebig,  Macagno,  and  Morley,  and  says  in  conclusion: 

Ich  glaube  hiermit  den  Nachweis  geliefert  zu  haben,  dass  die  ja  lange  Zeit  herrschend 
gewesene,  neuerdings  aber  mehrfach  wieder  in  Zweifel  gezogene  Annahme  einer  inner- 
halbenger  Grenzen  konstanten  Zusammensetzung  der  atmospharischen  Luft  that- 
sachlich  noch  zu  Recht  besteht,  insofem  alle  entgegengesetzten  Beobachtungen  bis 
jetzt  nicht  geniigend  verbiirgt  scheinen. 

In  testing  his  extremely  complicated  apparatus  for  gas-analysis, 
Geppert^  made  a  number  of  air-analyses,  employing  the  hydrogen  ex- 

*  Geppert,  Die  Gasanalyse  und  ihre  physiologische  Anwendung  nach  verbesserten 
Methoden,  Berlin,  1885,  p.  96. 


History  of  Air-Analysis 


55 


plosion  for  the  determination  of  oxygen*  A  sufficiently  large  sample  was 
taken  to  eliminate  the  errors  incidental  to  working  with  minute  quantities 
of  gas  such  as  would  be  obtained  from  blood;  the  results  given  in  table  38 
were  obtained  for  the  percentage  of  oxygen.  The  extremely  low  value 
of  20.68  is  attributed  by  the  author  to  a  defect  in  the  particular  eudiometer 
used  for  this  single  determination.  The  author  points  out  that  if  one 
wishes  to  make  exact  gas-analyses  it  is  desirable  to  test  the  eudiometer 
previously  with  normal  air. 

Table  38. — Percentages  of  oxygen  determined  on  atmospheric  air  by  Geppert. 


Series  1. 

Series  2. 

Series  3. 

Series  4. 

Series  5. 

Series  12. 

p.  ct. 

p.ct. 

p.ct. 

p.ct. 

p.ct. 

p.ct. 

20.910 

20.848 

20.885 

20.948 

20.88 

20.96 

20.928 

20.863 

20.904 

20.912 

20.91 

20.97 

20.929 

20.837 

20.912 

20.93 

20.97 

.... 

.... 

.... 

.... 

20.68 
20.91 

Contemporaneously  with  Morley  and  von  Jolly,  but  working  entirely 
independently,  Hempel,  employing  potassium  pyrogallate  as  the  absorb- 
ing agent,  began  a  research  on  the  composition  of  the  air.^  In  1877  he 
found,  as  the  result  of  many  analyses,  differences  so  great  as  to  be  ex- 
plainable only  on  the  ground  of  imperfect  technique.  Subsequent  de- 
velopment of  apparatus  and  method  yielded  a  procedure  so  accurate  that 
duplicate  analyses  of  each  day's  sample  did  not  vary  from  one  another 
by  more  than  0.02  per  cent.  On  five  different  days  in  the  fall  of  1877  he 
found  20.89,  20.76,20.96,  20.91,  and  20.90  per  cent  of  oxygen,  respectively. 
In  1879,  analyses  were  made  in  April  and  May  as  follows: 


p.  ct. 

Apr.  24 21.16 

Apr.  25 20.91 

Apr.  26 20.92 


p.  ct. 

Apr.  27 20.83 

Apr.  28  20.87 

Apr.  29 20.70 


Apr.  30 20.83 

May   1  20.82 

May  3  20.55 


By  means  of  the  improved  apparatus,  an  interesting  comparative 
series  of  analyses  was  made,  samples  of  air  being  collected  in  July  1883, 
simultaneously  by  Professor  Hempel  in  Dresden  and  Professor  E.  Hagen 
on  the  steamer  between  Liverpool  and  New  York,  all  samples  being  taken 
at  8  a.  m.  The  results  are  given  in  table  39. 
Table  39. — Determinations  of  oxygen  in  atmospheric  air,  collected  at  sea  and  in  Dresden. 


Date. 

At  sea. 

Dresden. 

Date. 

At  sea. 

Dresden. 

1883. 

July  22 
July  23 
July  24 
July  25 
July  26 

2^6.94 
20.80 
20.88 
20.91 
20.95 

20.93 
20.92 
20.86 
20.91 

1883. 

July  27 
July  28 
July  29 
July  30 

20.87 
21.09 
20.91 
21.01 

20.92 
20.97 
21.01 
20.95 

1  Hempel,  Berichte  der  deutschen  chemischen  Gesellschaft,  1885, 18,  p.  267. 


56 


Composition  of  the  Atmosphere 


Using  identically  the  same  apparatus,  Oettel  in  Hempel's  labora- 
tory determined  each  day  the  carbon  dioxide  and  oxygen  of  Dresden  air 
from  October  12,  1884,  to  December  24,  1884.  Oettel's  results  are  ex- 
pressed in  the  form  of  a  curve  not  easily  reproduced,  but  table  40  shows 
his  results  from  November  8  to  18.  The  duplicate  analyses  permit  an 
estimate  of  the  accuracy  of  the  method  he  used.  The  figures  also  show 
the  general  extent  of  the  variations  he  observed  in  the  oxygen  and  carbon- 
dioxide  content  of  the  atmosphere. 

Table  40. — Determinations  of  oxygen  in  Dresden  air,  made  by  Oettel. 


Date. 

Oxygen  and 
carbon 
dioxide. 

Carbon 
dioxide. 

Date. 

Oxygen  and 
carbon 
dioxide. 

Carbon 
dioxide. 

1884. 

Nov.      8 
Nov.      9 
Nov.    10 
Nov.    11 
Nov.    12 
Nov.    13 

p.ct. 
i  20.84 
I  20.85 
J  20.87 
}  20.89 
\  20.88 
}  20.86 
\  20.90 
?  20.91 
\  20.74 
?  20.75 
S  20.77 
I  20.75 

p.ct. 

0.036 
.037 
.039 
.041 
.050 
.055 
.0389 
.0391 
.040 
.044 
.044 
.048 

1            1S84. 

Nov.    14 
Nov.    15 
Nov.    16 
Nov.    17 
Nov.    18 

p.ct. 

S  20.81 
/  20.78 
\  20.82 
I  20.79 
\  20.80 
I  20.83 
\  20.86 
I  20.84 
\  20.92 
I  20.92 

p.ct. 

0.049 
.054 
.038   , 
.041 
.0416 
.043Q 
.040 
.037 
.040 
.044 

A  few  months  later  Hempel,  in  defending  the  use  of  potassium  pyrogal- 
late  from  the  criticism  raised  by  Kreusler,^  published  further  experiments 
on  air. 2  In  one  sample  of  air  he  reports,  as  the  result  of  four  determina- 
tions in  which  carbon  dioxide  and  oxygen  were  collectively  absorbed, 
20.936,  20.938,  20.938,  and  20.938  per  cent,  respectively— an  agreement 
that  is  striking. 


Table  41. — Determinations  of  oxygen  in  atmosph 

eric  air,  made  by  Hempel. 

1         Date. 

Oxygen  and 
carbon 
dioxide. 

1 

Carbon       Average    ; 
dioxide.       oxygen. 

Date. 

dioxide.     !  <i'o^d«- 

Average 
oxygen. 

18S5. 

Feb.    3 

1 

1     Feb.    6 

'     Feb.    7 

Feb.    8 

Feb.    9 

Feb. 10 

1 

p.ct. 

\  20.960 
/  20.955 
\  20.970 
)  20.980 
\  20.945 
"/  20.960 
^21.001 
)  20.991 
\  20.969 
■/  20.979 
\  20.961 
}  20.958 

p.ct. 

0.035 
.035 
.035 
.034 
.034 
.034 

p.  ct. 
20.920   j 

20.939 

20.917 

20.962 

20.940 

20.926 

18S5. 

Feb.  11 
Feb. 12 
Feb. 13 
Feb.  14 
Feb. 15 

p.  ct. 

\  20.950 
1  20.944 
{  20.965 
/  20.968 
i  20.958 
}  20.974 
20.932 
/  20.946 
{  20.975 
I  20.971 

p.ct. 

0.037 
.035 
.036 
.034 
.035 

p.ct. 

20.910 
20.932 
20.930 
20.905 
20.938 

Beginning  with  February  3,  1885,  Hempel  made  duplicate  analyses  of 
air  nearly  every  day  until  March  28.     The  results  for  the  first  half  of 

^  Kreusler,  loc.  cit. 

2  Hempel,  Berichte  der  deutschen  chemischen  Gesellschaft,  1885,  18,  p.  1800. 


History  of  Air-Analysis  57 

February  are  given  in  table  41  as  illustrative  of  the  accuracy  of  his  work 
and  of  the  magnitude  of  the  fluctuations  experienced  by  him. 

An  examination  of  all  of  his  results  shows  a  minimum  of  20.877  per 
cent,  a  maximum  of  20.971  per  cent,  with  a  difference  of  0.094  per  cent, 
and  an  average  of  20.93  per  cent  of  oxygen.  Hempel  points  out  that  his 
results  compare  favorably  with  those  of  Kreusler,  who  found  20.911  per 
cent,  and  of  Morley,  who  obtained  20.949  per  cent,  each  investigator 
using  a  wholly  different  method. 

Obviously  to  three  such  skilled  experimenters  as  Morley,  Kreusler, 
and  Hempel,  the  uncertainty  regarding  the  general  question  as  to  the 
constancy,  or  lack  of  constancy,  of  the  oxygen  content  of  the  air  was 
somewhat  disconcerting,  and  it  is  not  surprising  that  we  find  them  in  1886 
engaging  in  a  cooperative  investigation.  Morley  in  Cleveland,  Kreusler 
in  Bonn-Poppelsdorf,  and  Hempel  in  Dresden  collected  samples  at  the 
same  time,  making  due  allowances  for  geographical  location.  In  addition, 
Hempel  secured  the  aid  of  Pusinelli,  who  took  samples  in  Para,  Brazil, 
and  of  Schneider,  who  simultaneously  took  samples  at  Tromso  in  Norway. 
Thus  the  times  for  collecting  were : 

Cleveland 8^  18'°  a.m.     i    Dresden 2**  SS""  p.m. 

Para 10   31    a.m.     I    Tromso 3  00    p.m. 

Bonn 2    12    p.m.     1 

Kreusler,^  who  made  the  determinations  with  his  glowing  copper- wire 
eudiometer,  published  his  results  independently  shortly  before  Hempel's 
paper^  appeared. 

Kreusler  abates  somewhat  his  criticism  of  the  pyrogallic-acid  method, 
but  still  adheres  to  von  Jolly's  copper  eudiometer.  His  results  need  not 
here  be  reproduced  in  full,  as  they  are  in  part  incorporated  with  those  of 
Hempel  and  Morley  in  table  42.  Kreusler  found  percentages  of  oxygen 
ranging  from  20.907  to  20.939,  substantiating  his  earlier  findings  and  be- 
lief that  the  oxygen  fluctuations,  in  spite  of  changes  in  meteorological 
conditions,  are  small.  The  average  is  20.922  per  cent,  which  is  a  little 
higher  than  the  average  of  his  earlier  results,  ?.  <?.,  20.911.  Hempel's 
summary  of  the  complete  investigation  includes  the  results  of  both  Kreus- 
ler and  Morley.  A  specimen  set  of  records  from  April  1  to  April  11,  1886, 
will  serve  to  show  both  the  agreement  of  duplicates  and  the  variations 
experienced  in  various  places.  The  samples  from  Tromso,  Dresden,  and 
Para  were  all  analyzed  alike,  in  that  both  oxygen  and  carbon  dioxide  were 
simultaneously  absorbed.  Oxygen  alone  was  determined  in  the  samples 
collected  in  Bonn  and  Cleveland. 

The  Tromso  analyses  usually  showed  an  agreement  within  0.01  per 
cent  on  the  same  day;  on  several  occasions  the  difference  was  0.03  per 
cent,  but  the  average  for  each  day  showed  a  fluctuation  ranging  from  21 
per  cent  down  to  20.90  per  cent.     It  should  be  borne  in  mind  that  the 

1  Kreusler,  Berichte  der  deutschen  chemischen  Gesellschaft,  1887,  20,  p.  991. 

2  Hempel,  ibid.,  p.  1864. 


68 


Composition  of  the  Atmospheke 


results  obtained  from  the  Tromso  samples  were  for  oxygen  plus  carbon 
dioxide  and  not  for  oxygen  alone. 

Table  ^2.— Comparative  study  of  the  oxygen  content  of  air,  made  by  Kreusler,  Hempel, 

and  Morley. 


Date. 

Oxygen  and  carbon  dioxide. 

Oxygen. 

Tromao. 

Dresden. 

Para. 

Bonn. 

Cleveland. 

Found. 

Average. 

Found. 

Average. 

Found. 

Average. 

Found. 

Found. 

Average 

1886 

,     P.ct. 

V.ct. 

p.ct. 

p.ct. 

V.ct. 

p.ct. 

p.  ct 

^A^L 

J:  ''^A 

Apr.    1 

1    20.95 

20.94 

20.94 

20.94 

20.91 

20.91 

20.93 

20.90 

20.90 

1    20.93 

20.93 

20.91 

20.90 

Apr.    2 

20.94 

20.94 

20.96 

20.96 

.... 

.... 

20.93 

20.93 

20.93 

:   20.94 

20.96 

20.93 

Apr.    3 

.... 

20.93 

20.93 

.... 

2b.9i 

20.91 
20.92 

20.92 

Apr.    4 

20.94 

20.94 

20.95 

20.95 

2b.9i 

2b.9i 

20.93 

20.93  > 

20.93 

1 

20.95 

20.92 

20.93 

Apr.    5 

20.95 
!    20.94 

20.95 

20.93 
20.94 
20.94 

20.94 

20.92 
20.93 

20.93 

20.92 

20.94 
20.94 

20.94 

Apr.    6 

20.97 
20.97 

20.97 

20.92 
20.94 

20.93 

20.95 
20.95 

20.95 

20.92 

20.93 
20.93 

20.93 

Apr.    7 

20.96 
20.96 

20.96 

20.89 
20.90 

20.90 

20.93 
20.92 

20.93 

20.92 

20.93 
20.93 

20.93 

Apr.    8 

.... 

.... 

.... 

20.90 
20.90 

20.90 

2b.9i 

20.91 
20.91 

20.91 

Apr.    9 

20.97 
20.95 

20.96 

20.91 
20.91 

20.91 

20.96 
20.96 

20.96 

2b.96 

20.93 
20.93 

20.93 

Apr.  10 

20.96 
20.95 

20.96 

20.93 
20.92 

20.93 

20.95 
20.95 

20.95 

2b.93 

20.93 
20.93 

20.93 

Apr.  11 

.... 

20.92 
20.91 

20.92 

20.91 
20.91 

20.91 

20.92 

20.92 
20.93 

20.93 

The  Dresden  samples  showed  very  slight  variations,  the  results  for 
the  same  day  usually  being  very  close,  and  commonly  exactly  alike.  In 
one  instance  only  was  there  a  difference  of  0.02  per  cent.  The  average 
for  different  days  ranged  from  20.96  per  cent  down  to  20.88  per  cent;  the 
maximum  and  minimum  did  not  coincide  with  those  for  Tromso. 

For  the  Para  samples  the  agreement  for  individual  days  was  likewise 
very  close,  although  in  all  not  so  many  samples  were  analyzed.  The 
agreement  was  within  0.01  or  0.02  per  cent,  the  difference  in  no  instance 
being  more  than  0.02  per  cent.  The  average  for  the  day  showed  fluctu- 
ations from  20.99  to  20.86  per  cent. 

The  analyses  made  in  Tromso,  Dresden,  and  Para,  therefore,  since 
they  all  represent  the  content  of  oxygen  plus  carbon  dioxide,  are  directly 
comparable  with  one  another,  the  averages  being  respectively:  For  Trom- 
so, 20.946  per  cent;  for  Dresden,  20.928  per  cent;  and  for  Para,  20.923 
per  cent.  On  the  supposition  that  the  carbon-dioxide  content  remained 
on  the  average  0.03  per  cent,  and  assuming  that  it  was  somewhat  higher 
in  the  day  period  than  in  the  night,  Hempel  computed  the  average  oxygen 
content  by  deducting  0.03  per  cent,  and  found  for  Tromso,  20.92  per  cent; 


History  of  Air-Analysis 


59 


for  Dresden,  20.90  per  cent;  and  for  Para,  20.89  per  cent,  respectively. 
In  the  same  month,  therefore,  the  oxygen  content  in  the  neighborhood  of 
the  poles  was  somewhat  higher  than  in  the  neighborhood  of  the  equator. 

In  the  oxygen  values  found  in  Bonn,  only  a  smgle  observation  for  each 
day  was  given,  or  possibly  these  figures  represent  the  average  for  each  day. 
They  varied  from  20.94  to  20.90  per  cent. 

The  values  for  the  Cleveland  samples,  which  also  represent  the  oxygen 
content  alone,  showed  usually  an  exact  agreement  between  duplicates  on 
the  same  day,  and  in  only  a  few  instances  was  there  a  discrepancy  of  0.01 
per  cent.     The  averages  ranged  from  20.95  to  20.90  per  cent. 

The  total  averages  for  these  two  places  are:  For  Bonn,  20.922  per  cent; 
for  Cleveland,  20.933  per  cent. 

The  total  average  value  obtained  by  the  analysis  of  203  different  air 
samples,  collected  in  five  different  places,  and  analyzed  by  three  different 
methods,  is  20.91  per  cent  of  oxygen. 

On  an  expedition  to  Cape  Horn  to  observe  the  transit  of  Venus, 
Muntz  and  Aubin^  made  analyses  of  air  taken  at  Orange  Bay,  using  the 
eudiometer  of  Regnault  and  Reiset  as  modified  by  Schloesing.  Their 
results  are  given  in  table  43.  The  authors  conclude  that  the  average  oxy- 
gen percentage  in  the  air  taken  near  Cape  Horn  is  less  than  the  value 
found  by  Regnault  in  Paris,  but  essentially  that  found  in  different  parts 
of  the  world;  they  believe,  however,  that  the  proportions  of  oxygen  and 
nitrogen  are  subject  to  variations  which  are  within  the  narrow  limits  es- 
tablished by  Regnault. 
Table  43. — Determinations  of  oxygen  in  atmospheric  air,  made  by  Muntz  and  Avbin. 


Date. 

Oxygen. 

Date. 

Oxygen. 

! 

1           Date. 

Oxygen. 

1883. 

p.  ct. 

1883. 

V.ct. 

!            1883. 

V.ct. 

May    10 

20.86 

May    17 

20.97 

July     22 

20.90 

May    11 

20.92 

May    18 

20.85 

July     22 

20.95 

May    12 

20.93 

May    19 

20.88 

1     July     29 

20.89 

May    13 

20.89 

May    19 

20.72 

Aug.      1 

20.78 

May    14 

20.95 

May    22 

20.87 

Aug.      2 

20.79 

May    15 

20.90 

May    24 

20.84 

Aug.      2 

20.83 

May    16 

20.72 

July       5 

20.83 

! 

Phosphorus  as  an  absorbent  of  oxygen  again  made  its  appearance  in 
air-analysis  in  the  hands  of  Ebermayer,^  who  analyzed  air  from  forests  in 
1885.     He  found  in  free  atmospheric  air  20.82  per  cent  of  oxygen. 

Breslauer^  analyzed  air  in  Brandenburg  at  least  once  a  month,  some- 
times as  frequently  as  two  or  three  times  each  month  from  January  to 
December.  As  an  average  of  20  analyses  he  gives  20.934  per  cent,  with 
a  minimum  of  20.895  and  a  maximum  of  20.955  per  cent.* 

1  Muntz  and  Aubin,  Comptes  rendus,  1886,  1 02,  p.  421  oo«    u  ^      *^ 

2  Ebermayer,  Fortschritte  a.  dem  Gebiete  der  Agnkultur-Phys.,  9,  p.  229;  abstracted 
inChemischesCentralblatt,  1886,  17,p.770.  ^    ,    .     „       ^    ^  xr    t>    r 

3  Breslauer,  Die  chemische  Beschafifenheit  der  Luft  m  Brandenburg  a.  H.,  Berlin, 
1886. 

4  Breslauer,  Deutschen  Medizinal-Zeitung,  1885,  6,  p.  1. 


60  Composition  of  the  Atmosphere 

In  connection  with  his  research  on  the  influence  of  the  ingestion  of 
food  on  metaboUsm,  Magnus-Levy ^  in  Zuntz's  laboratory,  described  a 
new  form  of  gas-analysis  apparatus  in  which  phosphorus  is  used  to  absorb 
oxygen.  To  demonstrate  the  accuracy  of  his  apparatus  he  reports  the 
determinations  of  the  oxygen  percentages  in  a  series  of  16  air-analyses, 
as  follows: 


P.ct. 

p.ct. 

p.ct. 

p.ct. 

20.90 

20.90 

20.73? 

20.88 

20.93 

20.88 

20.81 

20.86 

20.89 

20.97? 

20.90 

20.90 

20.89 

20.82 

20.90 

20.88 

Leduc^  in  1890,  recognizing  the  discrepancy  between  the  results  of 
Regnault  on  the  one  hand  and  of  Dumas  and  Boussingault  on  the  other, 
sought  to  explain  the  difference  on  the  grounds  of  slight  errors  in  Reg- 
nault's  determinations  of  the  densities  of  the  gases.  One  year  later 
Leduc,^  having  questioned  the  accuracy  of  absorbing  oxygen  by  copper, 
inasmuch  as  nitrogen  combined  with  the  hydrogen  of  the  reduced  copper, 
used  Brunner's  method,  in  which  the  oxygen  is  absorbed  by  phosphorus, 
and  weighed  both  the  air  and  the  nitrogen  remaining.  Two  experiments 
carried  out  with  the  greatest  care  gave  23.244  and  23.203  per  cent  of  oxy- 
gen by  weight,  or  21.024  and  20.987  per  cent  by  volume,  respectively. 
The  author  obtained  the  same  results  by  determining  the  densities  of 
nitrogen  and  oxygen. 

Wanklyn  and  Cooper,^  using  the  pyrogallic-acid  method,  obtained  on 
three  samples  20,  20.8,  and  20.5  per  cent  of  oxygen,  respectively.  By 
explosion  with  hydrogen  they  obtained  21.34,  20.94,  and  21.34  per  cent 
of  oxygen. 

Using  an  alkaline  ferroso-tartrate  solution  for  an  absorbent,  de  Ko- 
ninck^  found  as  the  mean  of  four  determinations  21.00  per  cent  of  oxygen. 

Laulanie^  in  1894  published  the  description  of  a  eudiometer  in  which 
the  oxygen  was  determined  by  absorption  with  phosphorus.  He  claimed 
very  accurate  results,  with  a  constant  oxygen  percentage  of  20.9. 

Using  a  modified  Bunsen  apparatus,  Schaternikow  and  Setschenow^ 
made  analyses  of  laboratory  air  in  Moscow,  and  report  12  analyses  of  out- 
door air.  The  oxygen  percentage  ranged  from  20.874  to  21.036,  with  an 
average  of  20.962  per  cent. 

^  By  passing  a  measured  amount  of  air  and  nitric  oxide  through  hydri- 
odic  acid,  Kreider,^  in  New  Haven,  Connecticut,  determined  the  free 
iodine  thus  liberated  by  means  of  1/10  normal  arsenious  acid  by  titration. 
He  gives  a  series  of  results  with  outdoor  air  on  two  samples  collected  over 

;  Magnus-Levy,  Archiv  fiir  die  gesammte  Physiologic,  1894,  55,  p.  1. 

^  Ledue,  Comptes  rendus,  1890,  1 1 1,  p.  262. 

3  Leduc,  Comptes  rendus,  1891,  1 13,  p.  129. 

;  Wanklyn  and  Cooper,  Air  analysis,  London,  1890,  p.  35. 

5  de  Koninck,  Chemical  News,  1891,  64,  p.  45. 

*  Laulanie,  Archives  de  Physiologic,  1894, 26,  p.  739. 

Schaternikow  and  Setschenow,  Zeitschrift  fiir  physikalische  Chemie,  1895, 1 8,  p.  56.3 

Kreider,  Zeitschrift  fur  anorganische  Chemie,  1896,  13,  p.  423. 


History  of  Air-Analysis 


61 


water;  11  analyses  made  on  the  same  sample  of  air  gave  percentages  of 
oxygen  varying  from  20.91  to  21.19,  with  an  average  of  21.08,  and  on 
another  day  6  analyses  of  the  same  sample  of  air  gave  percentages  varying 
from  20.96  to  21.03,  and  averaging  20.99.  The  author  also  reports  two 
analyses  of  air  by  pyrogallic  acid,  showing  20.93  and  20.88  per  cent  of 
oxygen,  respectively. 

Employing  a  reaction  first  utilized  by  Winkler^  to  determine  the  oxy- 
gen dissolved  in  water,  Chlopin^  utilized  the  interaction  between  man- 
ganous  salt  and  oxygen  in  the  presence  of  potassium  iodide  to  determine 
the  oxygen  content  of  gaseous  mixtures  by  titration.  The  results  of  a 
series  of  analyses  of  the  air  taken  in  the  court  of  the  Hygienic  Institute  in 
Dorpat  are  given  in  table  44. 

Table  44. — Results  of  analyses  of  outdoor  aivy  made  by  Chlopin. 


Dat€. 

Oxygen. 

Date. 

Oxygen. 

1897. 

Feb.  25 

Mar.    4: 

Sample  a . . . . 

Sample  b  ... 
Mar.    8: 

Sample  a . . . . 

Sample  b   ... 

Mar.  13 

Mar.  19 

p.ct. 
20.86 

20.87 
20.89 

20.88 
20.94 
20.95 
20.90 

1897. 

Apr.     2 

Apr.  10 

June    1 

June    2 

June    5 

Average  . . 

p.ct. 
21.08 
20.97 
20.87 
20.91 
20.84 

20.905 

A  second  paper  by  Chlopin^  reports  analyses  of  outdoor  and  room 
air,  but  does  not  indicate  which  are  those  for  outdoor  air. 

Samojloff  and  ludin,^  describing  a  method  of  gas-analysis  in  which  a 
modified  Bunsen  apparatus  was  used,  have  published  a  considerable  num- 
ber of  analyses  of  outdoor  air.  Using  explosion  with  hydrogen  to  de- 
termine the  oxygen,  they  found  20.97,  20.97,  20.96,  21.00,  20.99,  20.99, 
21.01,  20.99,  20.96,  20.92,  20.97,  and  20.98  per  cent.  Two  analyses  with 
pyrogallic  acid  gave  20.91  and  21  per  cent  of  oxygen,  respectively. 

In  1902,  Krogh,  of  Copenhagen,  on  a  voyage  to  the  island  of  Disko, 
west  of  Greenland,  latitude  70°  north,  undertook  a  number  of  analyses  of 
atmospheric  air.  While  the  prime  object  of  his  research  was  to  study  the 
carbon-dioxide  tension  in  natural  waters  and  especially  in  the  sea,  these 
determinations  were  combined  with  direct  analyses  of  the  atmospheric 
carbon  dioxide  and  oxygen.  The  analyses  were  made  with  a  Haldane 
apparatus,  the  burette  of  which  contained  only  10  c.  c.  The  accuracy 
is  given  as  0.005  to  0.01  per  cent  and  the  numerous  double  determinations 
generally  agree  within  these  limits. ^    The  extensive  series  of  oxygen  de- 

1  Winkler,  Berichte  der  deutschen  chemischen  Gesellschaft,  1887,  21,  p.  2843.  Also 
ibid.,  1889,  22,  p.  1764. 

«  Chlopin,  Archiv  fur  Hygiene,  1899,  34,  p.  71. 

3  Chlopin,  Archiv  fiir  Hygiene,  1900, 37,  p.  329. 

4  Samojloff  and  ludin,  Le  Physiologiste  Russe,  1901,  2,  p.  171. 

5  Krogh,  Meddelelser  om  Groenland,  1904, 26,  p.333. 


Q2  Composition  of  the  Atmosphere 

terminations  obtained  at  this  time  are  reported  in  a  second  article  dis- 
cussing the  abnormal  carbon-dioxide  percentage  of  the  air  in  Greenland, 
and  the  general  relations  between  atmosphericand  oceanic  carbon  dioxide.  ^ 
On  22  days  samples  of  air  were  taken  from  a  number  of  different  places 
in  Greenland,  47  determinations  of  oxygen  being  made.  Excepting  one 
observation  of  20.84  per  cent,  which  was  attributed  by  the  author  to  a 
possible  analytical  error,  the  results  exhibit  variations  from  20.92  to 
21.015  per  cent.  Omitting  the  very  low  value  of  20.84  per  cent,  the 
average  of  the  determinations  is  20.960  per  cent.  Of  particular  signifi- 
cance is  the  fact  that  analyses  made  on  the  same  samples  showed  ex- 
tremely high  values  for  carbon  dioxide,  ranging  at  times  from  0.025  to 
0.07  per  cent. 

In  a  private  communication  from  Dr.  Krogh,  he  reports  that  a  series 
of  experiments  made  by  him  in  Greenland  in  1908  showed  oxygen  per- 
centages ranging  from  20.895  to  20.980,  with  an  average  of  20.945.  The 
unusually  high  carbon-dioxide  percentages  of  former  years  were  not  ob- 
tained, although  two  observations  gave  0.055  per  cent.  Dr.  Ki-ogh  also 
writes  that  in  1907  and  1908  Dr.  Lindhard  of  Copenhagen  made  obser- 
vations in  northeast  Greenland  (Denmark  Haven)  using  the  identical 
modified  Pettersson  apparatus  described  by  Dr.  Krogh  in  a  former  paper. 
He  reports  that  Lindhard's  results  would  be  liable  to  about  0.001  per  cent 
error,  and  they  agreed  perfectly  with  those  found  by  himself  on  the  west 
coast.  Lindhard  generally  found  about  0.035  per  cent  of  carbon  dioxide, 
but  on  one  or  two  days  it  was  below  0.03  per  cent,  and  on  5  days  out  of  23, 
0.04  per  cent  or  more.     The  maximum  value  found  was  0.062  per  cent. 

Dr.  Krogh,  commenting  upon  his  own  determinations  of  oxygen, 
writes  that  they  may  have  an  error  of  several  hundredths  of  a  per  cent,  as 
the  absolute  accuracy  may  be  much  affected  by  dirt  accumulating  in  the 
burette  and  by  variations  and  gradual  displacement  of  the  contained 
water.  He  says:  ''I  do  not  think  that  it  is  at  all  possible  to  determine 
oxygen  with  great  absolute  accuracy  except  by  analyzing  dry  and  in  a 
perfectly  clean  burette." 

It  should  be  borne  in  mind  that  Dr.  Krogh's  original  investigation 
dealt  simply  with  the  carbon-dioxide  tensions  in  air  and  in  water,  and  the 
oxygen  determinations  were  quite  incidental;  likewise,  the  oxygen  deter- 
minations in  1908  were  made  in  connection  with  experiments  with  the 
respiration  apparatus  for  determining  the  gaseous  exchange  of  Eskimos. 
As  one  of  the  foremost  investigators  in  gas-analysis,  Krogh's  experiences 
are  doublv  valuable.  ^ 


J  Krogh,  Meddelelser  om  Greenland,  1904,  26,  p.  409. 
On  a  recent  trip  to  Copenhagen,  I  was  accorded  the  privilege  of  seeing  a  new  gas- 
analysis  apparatus  devised  by  Dr.  Krogh  in  which  the  conditions  outlined  by  him  above 
^e  tully  reahzed.     Unfortunately,  at  the  time  of  going  to  press  with  this  report,  Dr. 
ts^Togh  has  not  completed  satisfactorily  his  experiments  with  this  apparatus. 


History  of  Air-Analysis 


63 


By  means  of  the  apparatus  described  by  At  water  and  Benedict,^ 
Miss  Charlotte  R.  Manning^  made  a  number  of  air-analyses  at  Middle- 
town,  Connecticut,  the  details  of  which  are  given  in  table  45. 

In  1904  Chandler^  reported  a  series  of  analyses  made  of  50  samples  of 
air  collected  in  the  New  York  subway,  the  content  of  oxygen  ranging  from 
20.3  to  20.8  per  cent.  Determinations  were  also  made  of  the  oxygen  in 
9  samples  of  surface  air;  the  results  ranging  from  20.6  to  20.9  per  cent. 

Table  45. — Determinations  of  oxygen  in  atmospheric  air,  made  at 
Wesleyan  University  in  Middletoum,  Connecticut. 


1 

Oxygen. 

i 

Date. 

Direction 
of  wind. 

I. 

II. 

III. 

'            1903. 

p.ct. 

p.ct. 

p.ct. 

1     Nov.    25 

w. 

20.91 

20.92 

1     Nov.    27 

w. 

20.95 

21.00 

20.93 

1     Nov.    30 

sw. 

21.09 

21.03 

1     Dec.      4 

NE. 

21.05 

20.97 

20.97     i 

SW. 

21.01 

21.00 

Dec.      5 

NNW. 

20.97 

20.99 

NW. 

21.01 

20.99 

i     Dec.      7 

W. 

20.93 

20.92 

20.90 

I 

w. 

21.01 

21.00 

t 

Pecoul  and  Gizolme*  published  in  1903  the  description  of  their  method 
of  air-analysis,  in  which  they  employed  a  unique  absorption  apparatus 
and  potassium  pyrogallate.  They  also  published  the  results  of  an  analy- 
sis of  an  air  sample  collected  in  Paris  at  Place  Lobau,  the  percentage  of 
carbon  dioxide  obtained  being  0.03  and  of  oxygen  20.85. 

Utilizing  the  extremely  ingenious  manometer  and  compensating  de- 
vice of  his  earlier  apparatus,  Pettersson  and  Hogland*  so  modified  this 
apparatus  as  to  determine  not  only  the  carbon  dioxide  but  also  the  oxygen, 
using  sodium  hydrosulphite  as  the  absorbing  agent.  They  report  the 
average  of  all  the  oxygen  determinations  made  by  them  in  Stockholm  in 
October,  November,  and  December  1889  as  20.940  per  cent.  Unfortu^ 
nately,  although  the  authors  promised  further  details  and  additional  re- 
sults, no  published  report  has  as  yet  appeared;  nor  did  a  personal  visit 
to  Stockholm  result  in  obtaining  further  information. 

That  this  method  was  extremely  promising  was  foreseen  by  Jaquet,* 
who,  in  connection  with  the  development  of  his  most  ingenious  respiration 
apparatus,  felt  the  imperative  need  of  exact  oxygen  determinations.  Em- 
ploying an  apparatus  modeled  after  the  design  of  Pettersson,  but    using 

^  Atwaterand  Benedict,  Carnegie  Institution  of  Washington  Publication  No.  42, 1905. 

'  Unpublished  data  from  laboratory  note-book. 

»  Chandler,  The  air  of  the  subway.  New  York,  1904  (privately  printed). 

*  Pecoul  and  Gizolme,  Annales  d  Observatoire  Municipal  (Observatoire  de  Mont 
Souris),  Paris,  1903,  4,  p.  184. 

5  Pettersson  and  Hogland,  Berichte  der  deutschen  chemischen  Gesellschaft,  1889,  22, 
p. 3324. 

**  Jaquet,  Verhandlungen  der  naturforschenden  Gesellschaft  in  Basel,  1904, 15,  p.  252. 


64 


Composition  of  the  Atmosphere 


potassium  pyrogallate  as  the  reagent,  Jaquet  analyzed  a  number  of 
samples  of  outdoor  air  and  reports  the  results  in  support  of  his  con- 
tentions regarding  the  accuracy  of  his  apparatus.     These  are  given  in 

table  46. 

Table  46. — Results  of  air-analyses  made  by  Jaqitet. 


Sample 
No. 

Carbon 
dioxide. 

Oxygen. 

1 

2 

0^02 
.03 
.032 
.032 
.038 
.032 

.031 

p.ct. 
20.93 
20.935 
20.928 
20.928 
20.94 
20.94 

3 

4 

5 

6 

Average  . . 

20.934 

Staehelin,  using  the  same  apparatus  as  Jaquet,  reported  in  1907^ 
that  in  51  analyses  of  air  in  Basel  the  average  oxygen  content  Was  20.90 
per  cent.  The  average  value  was  found  only  in  22  samples.  Twice  the 
oxygen  was  less  than  20.89  per  cent  and  eight  times  larger  than  20.91  per 
cent.     The  extreme  values  were  20.875  and  20.94  per  cent. 

Using  the  gas-analysis  apparatus  in  Basel,  Gigon^  found  with  po- 
tassium pyrogallate  that  the  oxygen  content  of  the  air  near  the  laboratory 
varied  between  20.87  and  21.2  per  cent.  These  fluctuations  he  is  inclined 
to  attribute  to  the  fact  that  the  laboratory  is  in  the  center  of  the  city  and 
near  large  factories. 

In  connection  with  the  use  of  the  Zuntz-Geppert  respiration  apparatus, 
many  analyses  of  air  have  been  made  and  occasionally  such  analyses  are 
reported.  Few  have  greater  interest  than  those  published  by  Durig  and 
Zuntz'  in  connection  with  the  description  of  one  of  their  trips  into  the 
high  Alps. 

Table  47. — Results  of  air-analyses  made  by  Durig  and  Zuntz. 


Date. 

Place. 

Carbon 
dioxide. 

Oxygen. 

1903. 
Aug.     14 
Aug.     19 
Aug.     23 
Aug.    31 
Sept.     6 

Cold'Olen 

ao4 

.03 
.02 
.02 
.03 

2^6.88 
20.86 
20.89 

20.88 
20.87 

....Do 

Capanna  Margherita 

....  Do 

....Do 

In  1903  they  analyzed  free  air  at  Col  d'Olen  and  at  the  Capanna 
Margherita  on  the  summit  of  Monte  Rosa.  The  results  are  given  in  table 
47.    The  authors  state  that  these  results,  which  agree  with  their  numerous 

^  StaeheUn,  Verhandlungen  der  Naturforschenden  Gesellschaft  in  Basel,  1907, 19,  p.  9. 
Gigon,  Archiv  fiir  die  gesammte  Physiologic,  1911, 140,  p.  517. 
Sup  1  Bd^  1904      421^^^^^  ^^^  Anatomic  und  Physiologic,  Physiologische  Abtheilung, 


History  op  Air-Analysis 


65 


analyses  in  Berlin,  substantiate  the  belief  that  the  atmosphere  has  a  con- 
stant constitution  up  to  an  altitude  of  4600  meters. 

In  a  private  communication  Professor  Durig  writes  that  in  the  two 
expeditions  in  1903  with  Zuntz  and  in  1906^  with  Frau  Durig  and  others, 
he  made  over  100  analyses  of  air.  The  percentage  of  oxygen  was  always 
between  20.87  and  20.96.  On  the  Teneriffe  expedition  in  1907  he  found 
from  20.87  to  20.98  per  cent — limits  almost  exactly  those  experienced  in 
Vienna  and  on  Monte  Rosa. 

In  describing  his  extremely  accurate  and  ingenious  gas-analysis  ap- 
paratus, Haldane^  has  published  the  results  of  a  number  of  air-analyses. 
Four  analyses  of  the  same  sample  of  air  gave  the  following  percentages: 


Analysis. 

Oxygen. 

Carbon 
dioxide. 

1 

2 

3 

4 

Average 

20.930 
20.926 
20.931 
20.924 

0.025 
.030 
.035 
.030 

.030 

20.928 

The  author  concludes  that  20.93  per  cent  may  be  taken  as  the  true  per- 
centage of  oxygen  in  pure  air. 

Absorbing  the  oxygen  from  dry  air  by  means  of  heated  yellow  phos- 
phorus, Watson, 3  working  in  Guye's  laboratory  in  Geneva,  determined 
the  oxygen  in  air  collected  in  Geneva  and  on  some  of  the  nearby  moun- 
tains. In  describing  his  method,  he  includes  a  few  preliminary  results 
which  are  given  in  table  48. 

Table  48. — Analyses  made  by  Watson  of  air  collected  in  Svntzerland. 


Source  of  air. 


Laboratory,  Geneva  (alt.  300  m.) : 

July  11,  1910,  4  p.m 

July  12,  1910,  5  p.m 

May  19,  10  a.m 

Sal^ve  (alt.  1300  m.),  May  19,  10  a.  m 
Rochers  de  Naye  (alt.  2045  m.) : 

May  19,  10  a.m 

May  19,  5^30°'a.m 


Oxygen. 


p.  ct. 
20.96 
20.98 
21.02 
20.95 

21.02 
21.04 


p.ct. 

20.93 
20.95 
21.04 
20.93 


m. 


p.et. 


21.03 


*  Durig,  Archiv  fiir  die  gesammte  Physiologie,  1906,  1 13,  p.  213. 

'  Haldane,  in  The  investigation  of  mine  air,  by  Foster  and  Haldane,  London,  1905,  p. 
113.     See  also,  J.  S.  Haldane,  Methods  of  air  analysis,  London,  1912,  p.  44. 
'  Watson,  Journal  of  the  Chemical  Society,  August,  1911,  p.  1460. 


66 


Composition  of  the  Atmosphere 


SUMMARY  OF  HISTORICAL  DIGEST.^ 

While  the  earliest  studies  of  the  composition  of  the  atmosphere  can 
hardly  be  considered  as  giving  results  of  quantitative  significance,  these 
researches  stimulated  greatly  the  study  of  chemistry  in  general  and  air- 
analysis  in  particular,  the  great  interest  in  the  composition  of  the  atmos- 
phere leading  to  the  rapid  development  of  many  methods  of  analyses. 

Seldom  has  a  philosophical  instrument  or  a  chemical  process  attracted 
so  much  attention  as  did  the  eudiometer,  which  utilized  the  reaction  be- 
tween nitric  oxide  and  air.  Although  soon  discarded  for  methods  better 
founded  scientifically,  the  apparatus  nevertheless  was  a  ready  and  port- 
able means  for  increasing  the  interest  of  investigators  and  diffusing  a 
knowledge  of  the  composition  of  the  air.  The  successors  of  this  method, 
i.fi.,  methods  involving  the  use  of  absorbents  like  alkaline  sulphides  or 
phosphorus,  or  employing  explosion  with  hydrogen,  all  of  which  depended 
upon  volumetric  measurements,  soon  demonstrated  the  difficulties  in  air- 
analysis — difficulties  which  taxed  the  ingenuity  and  the  patience^  of  prac- 
tically all  the  prominent  chemists. 

One  figure  in  this  early  history  of  air-analysis  shines  out  above  all 
others— that  of  the  scholarly,  isolated  Scheele.  That  Scheele  may  rightly 
be  designated  as  the  pioneer  in  the  study  of  the  chemistry  of  the  air  few 
who  examine  the  literature  can  deny.  His  results,  while  admittedly  of  no 
quantitative  significance,  do  nevertheless  imply  a  knowledge  of  the  chem- 
istry of  the  air,  of  its  composition,  and  of  the  possibilities  of  change  in  its 
composition,  which  was  expressed  no  more  clearly  by  other  writers  many 
years  later. 

Eudiometric  observations  were  exclusively  relied  upon  during  the  first 
50  years  of  the  development  of  air-analysis,  but  later  gravimetric  methods 
were  introduced  by  Brunner  and  Dumas  in  which  the  oxygen  was  ab- 
sorbed by  copper  or  phosphorus,  and  was  subsequently  weighed.  Then 
there  followed  a  return  to  the  hydrogen-explosion  method,  which  was  ad- 
vanced to  the  highest  degree  of  accuracy  by  Bunsen,  Regnault,  Frankland 
and  Ward,  and  Morley.  Meanwhile  the  interesting  method  of  Liebig, 
employing  an  alkahne  solution  of  pyrogallic  acid,  and  the  copper  eudio- 
meter of  von  Jolly  made  their  appearance. 

In  all  of  these  earlier  researches  we  find  that  while  the  chemical  proc- 
esses involving  the  absorption  of  oxygen  from  the  atmosphere  were  capa- 
ble of  innumerable  refinements,  the  grossest  errors  were  due  to  purely 

•D  i,,^°-CO™Piii°g  the  historical  material  in  this  book  I  have  been  greatly  aided  by  Miss 
/  S^^'  "hrarian  of  the  William  Ripley  Nichols  Library  of  the  Massachusetts  Institute 
of  Technology;  and  Mrs.  Austin  Holden,  of  the  Library  of  the  American  Academy  of 
Arte  and  Sciences;  and  my  thanks  are  especially  due  to  Dr.  J.  S.  Billmgs  and  his  associate, 
Dr.  Henryk  Arctowsld.  of  the  New  York  PubUc  Library.  The  facilities  of  the  library  of 
the  Harvard  Medical  School,  the  Library  of  Congress,  and  the  Surgeon  General's  Library 
have  also  been  freely  drawn  upon. 

I  am  also  much  indebted  to  Dr.  E.  P.  Cathcart,  of  Glasgow,  1911-1912  Research 
Afisociate  of  the  Carnegie  Institution  of  Washington,  attached  to  this  laboratory,  for  his 
painstaking  and  critical  reading  of  the  entire  manuscript  of  this  book. 


History  of  Air-Analysis  67 

mechanical  reasons,  chiefly  to  the  solubility  of  gases  in  water,  the  diffi- 
culties of  physical  measurements,  the  lack  of  knowledge  concerning  the 
physical  properties  of  gases,  the  inadequate  and  incorrect  calibrations  of 
the  glassware  then  in  use,  improper  temperature  control,  and  the  imperfect 
preparation  of  the  hydrogen — these  factors  affecting  more  or  less  the  accu- 
racy of  the  data  obtained  with  the  earlier  methods. 

As  the  more  popular  chemical  processes  for  the  determination  of  oxy- 
gen in  the  air  have  varied  materially — the  eudiometric  method  first 
being  used,  then  the  gravimetric,  and  finally  the  eudiometric  method 
again — similarly  we  find  that  the  prevailing  opinion  has  fluctuated  with 
regard  to  the  constancy  or  lack  of  constancy  in  the  composition  of  the 
air.  When  the  eudiometer  was  first  used  it  was  firmly  believed  that  the 
oxygen  percentage  varied  enormously,  and,  indeed,  that  the  salubrity  of 
any  climate  was  directly  proportional  to  the  amount  of  oxygen  present. 
Just  at  this  time  Cavendish,  although  using  an  imperfect  apparatus, 
made  a  remarkable  series  of  experiments,  coming  to  the  conclusion  that 
the  composition  of  the  air  was  constant;  in  other  words,  that  there  were 
no  fluctuations  that  were  measurable  on  his  instrument. 

Then  followed  the  development  of  the  law  of  gases  and  of  union  by 
volume,  with  the  measurement  of  the  oxygen  and  nitrogen  in  the  air  as 
approximately  1  to  4,  which  led  to  the  belief  that  the  air  was  a  chemical 
compound,  having  the  formula  N4O.  This  belief,  however,  was  soon  dis- 
carded, inasmuch  as  it  was  found  possible  to  separate  the  nitrogen  and 
oxygen  by  mere  physical  processes,  particularly  that  of  diffusion.  Evi- 
dence began  to  be  accumulated  to  demonstrate  that  the  percentage  of 
oxygen  in  the  air  was  not  sufficiently  constant  to  justify  the  use  of  the 
formula  N4O;  indeed,  there  appeared  to  be  considerable  variation  in  the 
composition  of  the  air.  As  experimental  work  progressed,  however,  the 
variations  began  to  grow  less.  In  a  long  series  of  investigations,  covering 
50  years,  no  variations  in  the  oxygen  content  greater  than  0.15  per  cent 
were  found,  save  in  desultory  observations  made  under  conditions  that 
do  not  inspire  the  greatest  degree  of  confidence.  The  only  exception 
was  the  interesting  research  in  1887  of  von  Jolly  in  Munich,  who,  by  ab- 
sorbing the  oxygen  in  his  copper  eudiometer,  found  much  greater  varia- 
tions than  had  formerly  been  obtained.  Independently  and  simulta- 
neously, but  employing  a  somewhat  different  form  of  apparatus  with  the 
highest  grade  of  technique,  Morley  in  Cleveland  found  similar  results, 
although  the  fluctuations  were  much  smaller  than  those  found  by  von 
Jolly.  Morley's  experiments  continued  over  a  period  of  several  years, 
ultimately  resulting  in  the  belief  that  the  oxygen  content  of  the  air  was 
affected  by  downward  currents,  particularly  following  a  sudden  drop  in 
temperature.  The  researches  of  Morley  and  von  Jolly  stimulated  further 
study  and  were  followed  by  the  cooperative  investigations  of  Morley, 
Kreusler,  and  Hempel,  which  showed  that  under  proper  control  the 
fluctuations  formerly  found  in  part  disappeared. 


68 


Composition  of  the  Atmosphere 


Finally,  as  an  indication  of  the  present-day  conception  of  the  com- 
position of  the  atmosphere,  the  following,  written  by  F.  W.  Clarke^  in 
1908,  may  be  cited : 

In  a  roughly  approximate  way  it  is  often  said  that  air  consists  of  four-fifths  nitrogen 
and  one-fifth  oxygen,  and  this  is  nearly  true.  The  proportions  of  the  two  gases  are  almost 
constant,  but  not  absolutely  so;  for  the  innumerable  analyses  of  air  reveal  variations 
larger  than  can  be  ascribed  to  experimental  errors.  A  few  of  the  better  determinations 
are  given  m  the  subjoined  table  [table  49],  stated  in  percentages  by  volume  of  oxygen. 
They  refer,  of  course,  to  air  dried  and  freed  from  all  extraneous  substances. 

Some  of  these  variations  are  doubtless  due  to  different  methods  of  determination, 
but  others  can  not  be  so  interpreted.  Hempel,  comparing  his  analyses  of  air  from  Trom- 
soe,  Norway,  and  Para,  Brazil,  infers  that  the  atmosphere  is  sHghtly  richer  in  oxygen 
near  the  poles  than  at  the  equator,  an  inference  that  would  seem  to  need  additional 
data  before  it  can  be  regarded  as  established.  The  most  significant  variation  of  all, 
however,  has  been  pointed  out  by  E.  W.  Morley.^  As  oxygen  is  heavier  than  nitrogen 
it  has  been  supposed  that  the  upper  regions  of  the  atmosphere  should  show  a  small 
deficiency  in  oxygen,  as  compared  with  air  from  lower  levels;  although  analyses  of  samples 
collected  on  mountain  tops  and  from  balloons  have  not  borne  out  this  suspicion.  It  is 
also  supposed  that  severe  depressions  of  temperature,  the  so-called  "cold  waves,"  are 
connected  with  descents  of  air  from  very  great  elevations.  Morley's  analyses,  conducted 
daily  from  January,  1880,  to  April,  1881,  at  Hudson,  Ohio,  sustain  this  belief.  Every 
cold  wave  was  attended  by  a  deficiency  of  oxygen,  the  determinations,  by  volume, 
ranging  from  20.867  to  21.006  per  cent,  a  difference  far  greater  than  could  be  attributed 
to  errors  of  measurement.  Air  taken  at  the  surface  of  the  earth  seems  to  show  a  very 
small  concentration  of  the  denser  gas,  oxygen. 

Table  49. — Determinations  of  oxygen  in  air,  in  percentage  by  volume. 


Analyst. 

Locality. 

Number 

of 
analyses. 

Mini- 
mum. 

Maxi- 
mum. 

Mean. 

V.  Regnault    

R.  W.  Bunsen 

R.  Angus  Smith   

Do 

Paris 

j        v.ct. 

100     1   2n.Qi.'^ 

p.ct. 

20.999 

20.970 

21.02 

21.18 

20.939 

20.971 

21.00 

20.97 
20.95 

p.ct, 

20.960 

20.924 

20.943 

20.970 

20.922 

20.930 

20.92 

20.89 

20.864 

20.933 

Heidelberg 

28 
32 
34 
45 
46 
41 
28 
20 
45 

20.840 
20.78 
20.80 
20.901 

20.877 

20.86 
20.72 
20.90 

Manchester     

Mountains  of  Scotland 
Near  Bonn    

U.  Kreusler     

W.  Hempel 

Dresden     .... 

Do 

Tromsoe 

Do ■ 

Para  . 

A.  Muntz  and  E.  Aubin 
E.W.Morley    

Cape  Horn    

Cleveland,  Ohio    

2  S*^!^^'  ?^^^  P^  geochemistry,  U.  S.  Geological  Survey  Bulletin  330,  1908,  p.  38. 
Money,  Amencan  Journal  of  Science,  1879,  3d  ser.,  18,  p.  168;  1881,  22,  p.  417. 


PART  II. 

ANALYSES  OF  ATMOSPHERIC  AIR  MADE  AT  THE 
NUTRITION  LABORATORY. 

From  the  standpoint  of  pure  physiological  chemistry,  the  importance 
of  an  exact  knowledge  of  the  composition  of  the  air  entering  the  lungs  is 
obvious  when  one  attempts  to  consider  the  various  means  for  studying 
the  respiratory  exchange.  Every  living  individual  is  continually  taking 
into  the  lungs  air  of  a  certain  composition,  which  on  leaving  the  lungs  has 
a  different  composition.  By  knowing  the  volume  of  air  passing  through 
the  lungs  and  the  change  in  composition,  important  deductions  with  re- 
gard to  the  metabolic  processes  can  be  made.  Furthermore,  in  certain 
lines  of  physiological  experimenting,  it  is  customary  to  confine  a  subject 
inside  an  air-tight  chamber  through  which  a  current  of  ventilating  air  is 
passed,  the  changes  in  composition  of  the  air  inside  the  chamber  being 
accurately  measured.  Obviously,  here  again  it  is  necessary  to  know  the 
exact  oxygen  content  of  the  air  entering  the  chamber. 

Although  recognizing  that  the  evidence  thus  far  accumulated  shows 
slight  differences  in  the  percentage  of  oxygen  in  the  air,  experimenters  for 
the  most  part  have  been  content  to  assume  a  constancy  in  this  factor 
for  air  supplied  to  a  respiration  chamber  or  entering  the  lungs  through 
nose-pieces  or  a  mouth-piece  in  an  apparatus  requiring  special  appliances 
for  breathing.  Singularly  enough,  however,  while  assuming  a  certain 
degree  of  constancy,  investigators  have  been  at  variance  in  regard  to  the 
value  to  be  assigned  for  the  oxygen  content  of  the  air.  In  examining  the 
literature  one  finds,  even  in  recent  researches,  variations  in  the  assumed 
composition  all  the  way  from  20.88  to  20.96  per  cent.  With  the  Zuntz 
respiration  apparatus  and  with  the  Chauveau  and  Tissot  apparatus,  the 
changes  in  composition  of  the  air  passing  through  the  lungs  are  very  great, 
so  that  this  difference  in  assumed  composition  is  not  of  as  great  magni- 
tude as  it  is  with  other  forms  of  apparatus.  For  example,  air  entering 
the  lungs  may  be  assumed  to  contain  20.93  per  cent  of  oxygen,  and  de- 
terminations of  the  air  leaving  the  lungs  may  show  an  oxygen  content  of 
16.93  per  cent,  or  a  difference  of  4  per  cent.  Consequently  an  error  of 
0.04  per  cent  in  the  assumed  composition  of  the  air  entering  the  lungs 
would  only  make  an  error  of  1  per  cent  in  the  total  oxygen  determined. 

One  of  the  most  important  and  promising  methods  of  studying  the 
respiratory  exchange  is  that  elaborated  by  Professor  Jaquet  of  Basel,  and 
extensively  used  by  both  Staehelin*  in  Berlin  and  by  Grafe*  in  Heidel- 


1  Staehelin  and  Kessner,  Charit^-Annalen,  1909, 33,  p.  1. 
'  Grafe,  Zeitschrift  fur  physiologische  Chemie,  1910, 65,  p.  1. 


69 


70  Composition  of  the  Atmosphere 

berg.  This  apparatus  is  essentially  on  the  Pettenkofer-Voit  principle, 
in  that  a  current  of  fresh  air  constantly  passes  through  the  chamber. 
The  air  leaving  the  apparatus  is  analyzed,  the  change  in  composition 
being  assumed  to  have  resulted  from  the  metabolic  activity  of  the  subject 
inside  the  chamber.  In  his  modification  of  the  Pettenkofer-Voit  appara- 
tus, Jaquet  has  included  the  determination  of  the  oxygen  in  the  out- 
going air-current,  thus  obtaining  data  regarding  the  amount  of  oxygen 
used,  as  well  as  the  carbon  dioxide  produced.  With  a  large  ventilation 
the  oxygen  deficit  may  be  very  small  in  amount;  conversely,  the  smaller 
the  ventilation,  the  larger  will  be  the  deficit.  Unfortunately,  most  work- 
ers with  this  apparatus,  although  recognizing  the  fact  that  the  oxygen 
deficit  should  be  large  rather  than  small,  in  practice  frequently  do  not 
heed  it  and  many  experiments  have  been  reported  in  which  it  is  but  0.50 
per  cent.  Under  these  conditions,  therefore,  it  can  be  easily  seen  that  an 
error  in  assuming  the  oxygen  content  of  the  incoming  air  may  be  of  con- 
siderable moment,  for  each  0.01  variation  may  make  a  difference  of  2  per 
cent  in  the  determination  of  the  oxygen  absorbed.  It  might  further  be 
said  at  this  point,  although  it  is  not  necessarily  germane  to  this  discussion, 
that  the  small  oxygen  deficit  so  commonly  used  by  workers  with  the 
Jaquet  apparatus  is  likewise  enormously  affected  by  analytical  errors  in 
determining  the  oxygen  in  the  out  coming  air.  The  Jaquet  system  is 
simple,  and  has  many  advantages  in  its  favor,  but  in  using  it  an  exact 
knowledge  of  the  composition  of  the  air  entering  as  well  as  of  that  leav- 
ing the  chamber  is  of  fundamental  importance. 

A  knowledge  of  the  exact  oxygen  content  of  the  air  inside  the  respira- 
tion chamber  is  also  of  great  importance  in  using  the  Regnault-Reiset  type 
of  respiration  apparatus.  For  example,  assuming  that  the  air  in  a  chamber 
containing  1000  liters  has  an  oxygen  percentage  of  20.93,  the  oxygen  con- 
tent would  be  approximately  209.3  liters.  An  error  of  0.1  per  cent  in  the 
determination  of  the  oxygen  would  therefore  result  in  an  error  of  prac- 
tically 1  liter  in  the  total  amount  of  oxygen  residual  in  the  chamber,  so 
that  with  an  oxygen  consumption  of  approximately  15  liters  per  hour, 
the  error  in  the  determination  of  the  total  oxygen  consumption  might 
easily  amount  to  one-fifteenth,  or  approximately  6  per  cent. 

One  of  the  most  important  uses  of  the  determination  of  the  oxygen 
content  of  the  air  in  the  chamber,  how^ever,  is  not  so  much  to  obtain  an 
exact  knowledge  of  the  amount  of  oxygen  present  as  to  indicate  in  an 
elaborate  and  complicated  apparatus  the  presence  of  a  leakage  of  air  into 
or  out  of  the  system.  This  point  was  brought  out  in  a  former  publica- 
tion. ^  In  a  closed-chamber  apparatus,  it  is  obvious  that  with  an  initial 
volume  of  1000  liters  of  air  there  can  be  no  change  in  the  nitrogen  content 
by  virtue  of  metabolic  processes,  ^  so  that  from  hour  to  hour  it  should  re- 

^  Atwater  and  Benedict,  Carnegie  Institution  of  Washington,  Publication  No.  42, 
1905,  p.  93. 

*  Krogh,  Skandinavisches  Archiv  fiir  Physiologic,  1906, 18,  p.  364. 


Apparatus  and  Methods  71 

main  essentially  the  same.  If,  however,  there  is  a  leakage  of  air  out  of 
the  system  and  a  consequent  replenishment  of  oxygen  to  maintain  con- 
stancy in  volume,  obviously  there  would  be  a  loss  in  nitrogen.  On  the 
other  hand,  if  there  is  a  leakage  of  air  into  the  system,  less  oxygen  will  be 
required  to  obtain  constancy  in  volume,  and  the  percentage  of  nitrogen 
will  continually  increase.  By  making,  at  stated  periods,  determinations 
of  the  nitrogen  in  the  residual  air,  it  is  possible  not  only  to  detect  when 
there  has  been  a  leakage  of  air  into  or  out  of  the  system,  but  also  from  the 
results  obtained  to  compute  easily  the  magnitude  of  this  leakage.^  This 
principle  has  been  used  recently  by  RoUy^  in  making  experiments  with  a 
small  respiration  apparatus. 

At  this  point  it  should  be  stated  that  throughout  this  discussion  it  is 
considered  for  convenience  that  the  air  used  for  the  determinations  of  oxy^ 
gen  is  free  from  water  and  carbon  dioxide.  Furthermore,  since  the 
proportion  of  argon  and  the  rarer  gases  in  the  atmosphere  does  not  play 
any  role  in  this  research,  no  special  recognition  is  made  of  the  presence  of 
0.94  per  cent  of  argon.  It  is  therefore  assumed  that  the  air  consists  only 
of  nitrogen  and  oxygen,  and  that  after  the  absorption  of  the  oxygen  the 
residual  gas  is  pure  nitrogen. 

While  there  are  a  large  number  of  methods  for  determining  the  carbon 
dioxide  produced  by  the  body,  the  determination  of  the  oxygen  consump- 
tion is  at  best  a  very  difficult  procedure.  When  the  Regnault-Reiset 
type  of  apparatus  in  this  laboratory  has  been  thoroughly  tested  and  shown 
to  be  air-tight,  air-analyses  are  unnecessary;  nevertheless  for  long-con- 
tinued experiments,  periodical,  accurate  determinations  of  the  oxygen 
in  the  air  residual  in  the  chamber  are  important.  Consequently,  the 
physiological  importance  of  knowing  the  constancy  or  lack  of  constancy 
in  the  composition  of  the  air  justified  the  study  of  this  problem  by  the 
Nutrition  Laboratory. 

FUNDAMENTAL  ESSENTIALS  OF  ACCURATE  AIR-ANALYSES. 

Although  the  gravimetric  determination  of  oxygen  in  air  was  especially 
successful  in  the  hands  of  Dumas  and  Brunner,  it  is  too  time-consuming 
to  be  practicable  for  metabolism  experimentation,  and  hence  there  has 
been  a  general  trend  in  the  last  30  years  toward  the  volumetric  determina- 
tion of  oxygen  by  absorption  with  either  phosphorus  or  potassium  pyro- 
gallate.  An  apparatus  for  the  determination  of  oxygen  in  physiological 
laboratories,  to  be  successful  and  practical,  should  have  first  an  efficient 
absorbent  for  oxygen,  i.  e.,  the  last  traces  of  oxygen  should  be  readily 
absorbed;  second,  no  by-products  of  the  chemical  reaction  should  be 
given  off  into  the  residual  gas,  thereby  increasing  its  volume;  third,  tem- 
perature changes  in  the  apparatus  during  the  process  of  an  analysis  should 

1  For  an  elaboration  of  this  theory  and  its  successful  application,  see  Atwater  and 
Benedict,  loc.  cit.,  pp.  88-89,  and  93. 

2  Roily  and  Rosiewicz,  Deutsches  Archiv  fur  klinische  Medizin,  1911,  103,  p.  68. 


72  Composition  of  the  Atmosphere 

be  fully  compensated  or  readily  corrected;  fourth,  barometric  changes  in 
pressure  taking  place  during  an  analysis  should  be  fully  compensated; 
fifth,  there  should  be  an  equal  tension  in  the  gas  before  and  after  absorbing 
oxygen  in  the  final  measurement;  and  sixth,  the  contraction  in  volume  as 
measured  should  be  due  only  to  the  absorption  of  oxygen. 

Absorbents  for  oxygen.— Oi  the  numerous  absorbents  for  oxygen,  in- 
cluding phosphorus,  potassium  pyrogallate,  and,  more  recently,  sodium 
hydrosulphite,  there  seems  to  be  but  little  choice  with  regard  to  the  com- 
pleteness of  absorption.  Although  both  phosphorus  and  potassium 
pyrogallate  are  affected  somewhat  by  low  temperature,  when  properly 
handled  they  absorb  oxygen  completely.  While  the  same  is  true  of 
sodium  hydrosulphite,  certain  difficulties  in  the  way  of  handling  this  re- 
agent have  precluded  its  general  adoption  by  chemists.  ^ 

Formation  of  by-products.— The  absorption  of  oxygen  is  invariably 
an  oxidative  process.  Usually  the  products  of  oxidation  are  non-gaseous, 
particularly  when  phosphorus  and  metallic  absorbents  are  used.  On  the 
other  hand,  it  has  been  claimed  that  in  the  interaction  between  oxygen 
and  potassium  pyrogallate  a  small  amount  of  carbon  monoxide  is  formed. 
This  militated  greatly  against  the  use  of  potassium  pyrogallate  in  the 
earlier  stages  of  its  introduction,  but  in  more  recent  years  a  study  of  its 
composition  has  led  to  changes  in  the  general  method  of  using  this  re- 
agent so  that  the  formation  of  any  measurable  amount  of  carbon  monoxide 
has  been  practically  precluded;  hence  as  satisfactory  results  can  be  obtained 
with  potassium  pyrogallate  as  with  phosphorus. 

Correction  for  temperature  changes. — From  the  time  when  the  sample  of 
gas  is  first  measured  until  after  the  absorption  of  either  carbon  dioxide 
or  oxygen  and  its  subsequent  measurement,  there  should  be  no  material 
alteration  in  the  volume  of  the  gas  due  to  temperature.  Modern  ap- 
paratus corrects  for  these  temperature  changes  by  means  of  a  compensa- 
ting vessel  or  pipette  of  the  same  size  and  in  the  same  temperature  en- 
vironment as  the  vessel  used  for  measuring  the  sample.  Frequently 
both  vessels  are  immersed  in  a  water-bath  which  is  constantly  stirred  to 
secure  temperature  equilibrium. 

Barometric  fluctuations. — While  usuallj-  of  slight  moment,  inasmuch 
as  the  analyses  can  be  readily  carried  out  in  a  few  minutes,  barometric 
changes  should  also  be  taken  into  consideration.  Particularly  is  this  the 
case  in  exact  gas-analysis  when  the  period  of  contact  between  the  air 
and  the  various  reagents  must  be  longer  than  in  the  ordinary  technical 
analysis.    In  some  analyses  it  may  require  30  minutes  or  more  for  com- 

i^The  use  of  sodium  hydrosulphite,  employed  by  Tobiesen  (Skandinavisches  Archiv 
fOr  Physiologic,  1895,  6,  p.  278),  has  been  more  recently  brought  to  the  attention  of  physi- 
ologists by  Durig,  of  Vienna.  (See  Biochemische  Zeitschrift,  1907,  4.  p.  65.)  The 
necessity  for  preventing  the  corrosive  action  of  this  reagent  on  glass  nas  called  for  a 
certain  technique  that  is  not  readily  acquired;  for  example,  Durig  coats  the  inside  of  his 
pipette  thinly  with  gutta  percha.  The  absorption  coefficient  of  the  solution  of  this 
reagent  IS  extremely  high,  but  as  yet  the  chemical  has  not  come  into  general  use,  al- 
though It  can  now  be  readily  purchased  in  a  pure  form. 


Apparatus  and  Methods  73 

plete  absorption;  during  this  time  there  may  be  an  appreciable  barometric 
change.  Practically  all  modern  gas-analysis  apparatus  provides  for  this 
change  in  temperature  by  adjusting  the  compensating  pipette  so  as  to 
take  care  not  only  of  the  changes  in  temperature  but  likewise  changes  in 
barometric  pressure.  Under  these  conditions  it  can  be  safely  said  that 
within  reasonable  limits  all  changes  in  temperature  and  pressure  are  readily 
compensated  by  the  modern  compensating  pipette  of  the  best  forms  of 
gas-analysis  apparatus. 

Tension  of  aqueous  vapor. — The  varying  percentages  of  water  in  sam- 
ples of  air  and  the  differences  in  tension  of  the  aqueous  vapor  above  the 
absorbing  solutions  make  it  necessary  to  insure  that  the  tension  of  gases 
before  and  after  absorption  remains  exactly  the  same.  This  is  best  se- 
cured in  practically  all  modern  gas-analysis  apparatus  by  saturating  the 
gas  with  water- vapor  both  before  and  after  absorption.  A  satisfactory 
method  for  this  is  the  placing  of  a  few  drops  of  water  upon  the  surface 
of  the  mercury  which  is  ordinarily  used  as  the  liquid  for  inclosing  and 
measuring  the  sample.  Under  all  conditions,  therefore,  the  gas  as  meas- 
ured is  saturated  with  water-vapor  at  the  temperature  of  the  water-bath. 
If  in  the  compensating  pipette  both  water-vapor  and  a  slight  excess  of 
water  are  present,  then  the  tension  of  aqueous  vapor  is  exactly  the  same 
in  the  compensating  pipette  and  in  the  measuring  pipette. 

Contraction  in  volume  as  a  measure  of  the  oxygen  absorbed. — The  most 
difficult  condition  in  gas-analysis  apparatus  is  to  make  sure  that  the  con- 
traction in  volume  as  measured  is  due  only  to  the  absorption  of  oxygen. 
The  usual  procedure  in  measuring  the  gas  is  to  read  the  top  of  the  mer- 
cury meniscus;  obviously,  this  reading  gives  not  only  a  measurement  of 
the  gas  to  be  analyzed,  but  of  the  water-vapor,  and  also  of  the  liquid 
water  used  to  insure  constancy  in  the  tension  of  aqueous  vapor.  The  ab- 
sorption of  the  gas  to  be  measured  changes  the  level  of  the  mercury,  rais- 
ing it  materially;  it  is  assumed  that  all  of  the  liquid  water  adhering  to  the 
walls  of  the  tube  is  removed  by  the  mercury  as  it  rises,  and  that  when  the 
mercury  meniscus  is  again  read  the  decrease  in  volume  is  due  only  to  the 
absorption  of  gas,  the  volume  of  liquid  water  present  in  the  tube  above 
the  mercury  remaining  essentially  unchanged.  The  difficulties  experi- 
enced in  proving  this  assumption  have  been  practically  insuperable,  and 
it  has  been  necessary  to  resort  to  a  reading  of  the  water  meniscus,  which 
is  at  best  very  unsatisfactory.  Fortunately  for  purposes  of  compari- 
son, when  essentially  the  same  gas — as  atmospheric  air,  for  instance — is 
analyzed  day  after  day,  it  is  possible  to  arrange  the  conditions  so  as  to 
make  the  amount  of  water  adhering  to  the  walls  of  the  tube  practically 
constant  as  the  level  of  the  mercury  changes.  Theoretically,  therefore, 
the  best  method  for  analyzing  gases  is  to  measure  them  absolutely  dry 
both  before  and  after  absorption  in  a  perfectly  dry  and  clean  pipette  over 
absolutely  dry  and  clean  mercury.  These  conditions  Dr.  Krogh  has 
succeeded  in  securing  in  his  new  gas-analysis  apparatus,  which  unfortuna- 
tely has  not  as  yet  been  described. 


74 


Composition  of  the  Atmosphere 


Fig.  1. — Sond^n  air-analysis  apparatus. 

The  two  pipettes  A  and  B,  and  the  reagent  containers  C  and  D,  are  immersed  in  water  in  the 
glass  tank.  Stoi>-cocks  a,  b,  c,  and  d,  permit  intercommunication  of  all  parts.  Cabron- 
dioxide  percentages  are  read  directly  on  A,  and  orygen  percentages  directly  on  B.  Mercury 
reservoirs  F  and  E  are  connected  with  pipettes  A  and  B  respectively.  The  manometer  M  aids 
m  securing  equal  tension  in  A  and  B. 


Apparatus  and  Methods  76 

APPARATUS  AND  TECHNIQUE  USED  IN  THIS  RESEARCH. 

The  importance  of  securing  the  highest  degree  of  accuracy  in  these 
analyses  led  to  a  critical  examination  of  all  the  forms  of  gas-analysis  ap- 
paratus of  unusual  accuracy  now  in  use.  Special  attention  was  given  to 
the  apparatus  of  Haldane,^  Chauveau,^  and  Sond^n-Pettersson.^  After 
a  careful  personal  examination  had  been  made  of  practically  every  form 
of  exact  gas-analysis  apparatus  in  existence,  it  appeared  that  the  poten- 
tialities for  exact  analysis  were  greatest  with  the  Sond^n  apparatus.  Ac- 
cordingly I  visited  Stockholm  to  make  arrangements  for  securing  such  an 
apparatus,  but  on  my  arrival  was  much  discouraged  to  find  that  none 
thus  far  constructed  was  sufficiently  exact  for  the  research  proposed. 
Through  the  geniality  and  interest  of  Dr.  Klas  Sonden,  however,  I  was 
able  to  spend  considerable  time  with  him  in  discussing  the  conditions  to  be 
met;  as  a  result,  he  designed  and  superintended  the  construction  of  the 
apparatus  herein  to  be  described,  which,  we  believe,  fulfills  perfectly  all 
of  the  conditions  outlined  except  the  last,  i.  e.,  constancy  in  volume  of  the 
liquid  water  above  the  mercury. 

Since  Dr.  Sonden  had  previously  spent  a  great  deal  of  time  in  ex- 
perimenting with  the  hydrogen  method  for  determining  oxygen  and  the 
results  had  been  unsatisfactory,  it  was  decided  to  use,  as  the  absorbing 
reagent,  a  strong  solution  of  potassium  pyrogallate,  potassium  hydroxide 
being  used  to  absorb  carbon  dioxide.  To  insure  thoroughly  controllable 
temperature  conditions,  the  entire  apparatus,  including  both  the  two 
measuring  pipettes  and  the  containers  for  the  reagents,  is  immersed  in  a 
water-bath,  nothing  but  capillary  tubing  being  exposed  to  the  room  tem- 
perature. The  apparatus  is  constructed  entirely  of  glass,  and  neither  the 
reagent  nor  the  gas  is  in  contact  with  any  other  material.  The  gas 
volumes  are  measured  over  mercury  to  avoid  the  solubility  of  the  gases 
in  water,  and  a  few  drops  of  water  above  the  mercury  in  the  measuring 
pipette  insure  saturation  with  water-vapor  at  the  temperature  at  which 
the  gases  are  measured. 

In  using  the  apparatus  a  volume  of  air  is  first  measured,  the  tempera- 
ture, pressure,  and  tension  of  aqueous  vapor  being  exactly  equal  to  a 
confined  volume  of  air  in  a  compensating  pipette.  The  air  sample  is  then 
passed  into  a  strong  solution  of  potassium  hydroxide  by  means  of  which 
the  carbon  dioxide  is  absorbed.  The  gas  is  next  returned  to  the  original 
measuring-vessel  and  the  apparent  volume  arbitrarily  adjusted  so  as  to  be 
the  same  as  before  the  absorption  of  the  carbon  dioxide.  There  is  then 
a  slightly  decreased  pressure  of  the  confined  air  due  to  the  volume  of  car- 

1  Foster  and  Haldane,  The  investigation  of  mine  air,  London,  1905.  See,  also,  J.  S. 
Haldane,  Methods  of  air-analysis,  London,  1912. 

2  Chauveau's  apparatus  is  described  in  detail  by  Tissot,  Traits  de  physique  biolo- 
gique,  I,  pp. 709-723. 

3  Pettersson,  Zeitschrift  fur  analytische  Chemie.  1886,  25,  pp.  467  and  469;  Pettersson 
and  Palmquist,  Berichte  der  deutschen  chemischen  Gesellschaft,  1888,  21,  p.  21-29; 
Sonden,  Zeitschrift  fur  Instrumentenkunde,  1889, 9,  p.  472. 


76  Composition  of  the  Atmosphere 

bon  dioxide  absorbed.  The  volume  of  the  air  in  the  compensating  pipette 
is  also  adjusted  to  exactly  the  same  pressure  and  temperature  as  that  in 
the  measuring-vessel,  and  by  measuring  the  apparent  increase  in  volume 
of  the  air  in  the  compensating-pipette,  a  direct  measure  of  the  carbon 
dioxide  absorbed  is  obtained.  The  carbon-dioxide-free  air  is  now  passed 
into  the  potassium  pyrogallate  to  absorb  the  oxygen.  When  the  air  is 
again  returned  to  the  measuring-pipette,  the  volume  is  adjusted  so  that 
the  tension  of  the  residual  gas  (nitrogen  and  argon)  is  exactly  the  same  as 
the  tension  of  the  gas  in  the  compensating-pipette.  The  amount  of  con- 
traction in  volume  may  then  be  directly  read  as  the  percentage  of  oxygen 
in  the  air. 

detailed  description  op  the  apparatus. 

A  somewhat  diagrammatic  representation  of  the  various  parts  of  the 
apparatus  is  given  in  fig.  1 ;  the  apparatus  as  actually  in  use  is  shown  in 
the  frontispiece.  The  main  features  of  this  apparatus  are  two  calibrated 
measuring-pipettes  A  and  B;  two  reagent  containers  C  and  D;  a  delicate 
manometer  M,  and  a  series  of  glass  stop-cocks  permitting  intercom- 
munication between  all  parts. 

The  whole  apparatus  is  substantially  mounted  upon  a  heavy  block  of 
marble.  The  pipettes  and  reagent  containers  are  immersed  in  a  glass 
tank  filled  with  water,  which  is  supported  at  the  bottom  by  a  metal  ring 
support  firmly  fastened  to  two  nickel-plated  uprights  (81  cm.  high), 
while  a  similar  ring  holds  the  upper  part.  In  the  bottom  of  the  glass 
tank  are  four  holes,  through  which  the  ends  of  the  various  pipettes  and 
reagent  containers  pass,  these  passages  being  made  water-tight  by  rubber 
connections.  The  water  in  the  tank  is  stirred  by  allowing  a  current  of 
air  to  bubble  through  it.  Under  these  conditions,  therefore,  the  tempera- 
tures in  the  apparatus  are  uniform  throughout,  and  while  a  thermometer 
is  suspended  in  the  water-bath,  the  temperature  readings  made  with  it 
are  not  essential. 

The  two  measuring-pipettes  A  and  B,  the  two  reagent  reservoirs  C 
and  D,  and  the  manometer  M  are  connected  by  capillary  tubing  and  glass 
stop-cocks,  so  that  all  five  members  are  fused  together  into  one  whole. 
Stop-cock  a  connects  pipette  B  either  with  stop-cock  6,  which  controls 
the  entrances  to  the  two  analytical  reagent  reservoirs,  or  with  stop-cock 
d,  which,  in  turn,  connects  with  either  the  outdoor  air  or  with  the  right 
side  of  the  manometer  M.  Stop-cock  c  connects  pipette  A  with  either 
the  outside  air  or  with  the  left  side  of  the  manometer.  Stop-cocks  /  and 
e  at  the  bottom  provide  communication  between  the  leveling  reservoirs 
F  and  E  and  their  respective  pipettes  A  and  B.  The  best  quality  of  stout- 
walled  rubber  tubing  should  be  used  for  connecting  the  leveling  bulb  with 
the  stop-cocks  /  and  e.  This  is  important,  since  we  find  that  many  kinds 
of  rubber  tubing  contaminate  the  mercury,  so  that  a  thin  coating  of  sul- 
phide, which  interferes  seriously  with  the  accurate  reading  of  the  meniscus 
level,  forms  on  the  top. 


Apparatus  and  Methods  77 

Since  the  changes  in  the  level  of  the  mercury  in  pipette  A  are  slight 
(these  changes  corresponding  to  the  carbon-dioxide  percentages  of  normal 
air)  the  leveling  bulb  F  is  not  usually  moved.  On  the  other  hand,  the 
leveling  bulb  E  is  hung  alternately  on  the  upper  and  lower  hooks  in  order 
to  expel  air  from  pipette  B  into  the  solution  in  either  C  or  Z),  or  out  into 
the  air  at  the  completion  of  the  analysis.  Minor  changes  in  level  of  the 
mercury  in  the  two  graduated  pipettes  are  produced  by  pressure  on  the 
rubber  tubing  with  the  delicate  screw-cocks  P  and  N.  By  shutting  the 
glass  stop-cock  /  below  and  screwing  in  the  cock  P,  pressure  can  be  pro- 
duced against  the  rubber  tubing  so  as  arbitrarily  to  adjust  at  will  the 
level  of  mercury  in  the  capillary  portion  of  ^.  A  similar  adjustment  of  the 
mercury  level  in  pipette  B  may  also  be  made  by  means  of  the  screw-cock 
N,  In  the  manometer  M  a  small  drop  of  light  petroleum  oil  serves  as  an 
index.  When  the  stop-cocks  c  and  d  are  removed  so  that  there  is  atmos- 
pheric pressure  on  each  side,  this  globule  should  stand  in  the  exact  cen- 
ter of  the  manometer  if  the  apparatus  is  properly  leveled.  All  stop-cocks 
are  well  ground,  perfect  in  fit,  and  lubricated  by  a  thin  layer  of  mutton 
tallow.  The  two  calibrated  pipettes  A  and  B  may  be  designated  respect- 
ively the  compensating  and  the  measuring  pipettes,  although  measure- 
ments are  actually  made  in  both. 

Compensating  pipette. — The  compensating  pipette  is  used  not  only 
for  the  final  adjustment  of  the  volume  of  gas  in  the  measuring  pipette  B, 
but  also  for  reading  directly  in  its  lower  graduated  portion  the  percentage 
of  carbon  dioxide.  The  volume  of  this  pipette  from  the  zero  mark  to  the 
glass  stop-cock  is  60  cubic  centimeters.  The  graduations  demand  a  spe- 
cial discussion.  In  all  measurements  made  with  this  pipette,  the  gas  in 
both  A  and  B  is  under  definite,  though  slight,  decrease  in  tension.  If 
the  volume  of  gas  in  the  measuring  pipette  has  been  decreased  one-thou- 
sandth by  the  absorption  of  carbon  dioxide  by  the  potassium  hydroxide, 
to  adjust  the  air  in  the  compensating  pipette  to  the  same  tension,  the  vol- 
ume of  air  must  be  expanded  one-thousandth  by  lowering  the  mercury 
a  certain  amount  in  the  graduated  portion  of  the  tube.  In  the  graduation 
of  this  pipette,  therefore,  due  cognizance  has  been  taken  of  the  altera- 
tion in  pressure  in  the  pipette  B.  The  graduations  are  so  arranged  as  to 
make  the  instrument  direct  reading,  the  level  of  the  mercury  in  pipette 
A  indicating  the  percentage  of  carbon  dioxide  in  the  air  sample. 

This  instrument  was  primarily  designed  to  study  the  percentage  of 
oxygen  in  the  air-content  or  the  ventilating  current  of  a  respiration  cham- 
ber. Under  these  conditions  the  carbon  dioxide  may  at  times  be  nearly 
1  per  cent  of  the  air  and  the  deficiency  in  oxygen  approximately  the  same. 
The  pipette  A  is  so  constructed  that  percentages  of  carbon  dioxide  as 
great  as  1  per  cent  can  be  measured.  Each  small  division  indicates  0.01 
per  cent  and  tenths  of  divisions  are  readily  estimated  by  the  eye,  so  that 
records  may  be  obtained  with  three  significant  figures  when  the  percent- 
age of  carbon  dioxide  is  greater  than  in  normal  air. 


78  Composition  of  the  Atmosphere 

For  the  purpose  of  this  discussion,  however,  we  have  to  deal  only  with 
small  percentages  of  carbon  dioxide — never  over  0.08 — and  the  special 
extended  graduation  of  this  pipette  is  only  of  incidental  interest.  The 
variations  usually  found  in  the  carbon-dioxide  content  of  outdoor  air  are 
so  small  that  all  adjustments  of  the  mercury-level  can  be  made  by  the 
adjusting  screw  P  without  disturbing  the  leveling-bulb  F, 

Measuring  pipette. — The  measuring  pipette  B  has  two  bulbs,  the  zero 
mark  being  placed  slightly  below  the  lower  bulb.  Between  the  two  bulbs 
is  a  constricted  portion  which  is  graduated  and  represents  that  part  of 
the  pipette  corresponding  to  from  19.5  to  21.0  per  cent  of  the  total  volume. 
This  constriction  favors  the  accurate  determination  of  oxygen,  since  after 
the  gas  is  absorbed  from  a  sample  of  air  and  is  again  drawn  into  the  pipette, 
the  mercury-level  must  be  raised  a  sufficient  amount  to  correspond  to  the 
volume  of  oxygen  absorbed.  This  is  usually  between  19.5  to  21.0  per 
cent  in  experiments  with  the  respiration  chamber,  and  for  outdoor  un- 
contaminated  air  is  generally  not  far  from  20.940  per  cent.  The  gradua- 
tions are  such  that  each  scale  division  corresponds  to  0.01  per  cent,  and 
hence  direct  readings  may  be  accurately  made  to  0.001  per  cent.  To  avoid 
errors  in  parallax,  the  graduation  marks  on  both  pipettes  completely 
circle  the  glass.  The  total  content  of  pipette  B  is  60  c.  c.  A  few  drops  of 
water  are  placed  in  both  pipettes  A  and  B  and  the  air  is  thus  continually 
saturated  with  water-vapor. 

The  upper  end  of  each  pipette  is  connected  by  capillary  glass  tubing 
to  the  various  stop-cocks,  while  the  lower  end  passes  through  a  hole  in 
the  bottom  of  the  glass  reservoir  and  is  there  connected  with  the  adjusting 
screws  P  and  N,  the  stop-cocks  /  and  e,  and  the  leveling-bulbs  F  and  Ej 
respectively.  Special  water-tight  closures  are  necessary  where  the  end 
of  the  pipette  passes  through  the  glass.  These  are  shown  in  detail  in 
fig.l. 

After  the  absorption  of  oxygen,  the  level  of  the  mercury  in  pipette  B 
indicates  the  percentage  of  oxygen  in  carbon-dioxide-free  air.  When 
ordinary  outdoor  air  with  a  carbon-dioxide  content  of  but  0.030  per  cent 
is  to  be  considered,  it  matters  but  little,  so  far  as  the  expression  of  the 
percentage  of  oxygen  is  concerned,  whether  the  air  is  carbon-dioxide-free 
or  not,  since  in  one  case  the  proportion  would  be  20.93  c.  c.  of  oxygen  in 
100  c.  c.  of  air  and  in  the  other  20.93  c.  c.  in  100  c.  C.-0.03  c.  c,  or  99.97 
c.  c.  of  carbon-dioxide-free  air;  thus  the  percentage  would  not  be  measur- 
ably affected.  When,  however,  there  may  be  0.8  per  cent  of  carbon  di- 
oxide in  air  taken  from  a  respiration  chamber,  it  becomes  a  matter  of  some 
moment  whether  the  percentage  is  of  carbon-dioxide-free  or  of  carbon- 
dioxide-containing  air. 

After  the  absorption  of  the  carbon  dioxide,  the  mercury-level  in  the 
compensating  pipette  is  so  adjusted  that  the  air  in  this  vessel  is  under 
slightly  decreased  tension — the  decrease  in  tension  being  equivalent  to 
the  volume  of  the  carbon  dioxide  absorbed.     The  final  adjustment  of  the 


Apparatus  and  Methods  79 

gas  in  the  measuring  pipette  likewise  produces  a  corresponding  decreased 
tension.  As  the  pipette  is  graduated  in  percentages,  it  obviously  makes 
no  difference  whether  the  gas  measured  is  at  atmospheric  or  less  than  at- 
mospheric pressure,  provided  the  residual  gas  is  at  the  same  pressure. 
For  this  reason,  then,  when  the  level  of  the  mercury  in  the  measuring 
pipette  B  is  adjusted  after  the  oxygen  is  absorbed,  no  change  is  made 
in  the  level  of  the  mercury  in  the  compensating  pipette  A.  The  reading 
for  the  oxygen,  therefore,  represents  the  percentage  of  oxygen  in  carbon- 
dioxide-free  air. 

Reagent  containers. — To  insure  rapid  and  efficient  absorption,  the 
reagent  should  be  contained  in  a  vessel  capable  of  exposing  a  relatively 
large  area  of  reagent  to  the  gas.  Since  the  relation  between  the  area  and 
the  volume  of  gas  depends  in  large  part  upon  the  amount  of  gas  to  be 
absorbed,  in  the  case  of  carbon  dioxide,  of  which  no  more  than  1  per  cent 
is  ever  present,  the  area  may  be  very  much  less  than  with  oxygen  of 
which  over  one-fifth  is  absorbed.  The  forms  of  reagent  containers  found 
most  advantageous  for  this  type  of  apparatus  are  shown  as  C  and  D  in 
fig.  1.  As  will  be  seen,  the  general  structure  of  both  vessels  is  the  same, 
the  notable  difference  being  that  D  contains  a  large  number  of  short  glass 
tubes  which  increase  greatly  the  absorbing  surface.  To  prevent  the 
tubes  from  falling  out,  the  opening  at  the  bottom  is  somewhat  more  con- 
stricted than  in  C.  Each  container  is  so  constructed  that  when  filled 
with  the  reagent  the  level  inside  and  out  is  the  same;  special  marks  not 
only  on  the  inner  capillary  tube  but  also  around  the  outer  glass  envelope 
of  the  chamber  aid  in  introducing  the  proper  amount  of  reagent  and  in 
setting  the  level  of  the  reagent  in  the  capillary.  A  short  length  of  glass 
tubing  fused  to  the  chamber  projects  above  the  level  of  the  water  in  the 
tank  and,  being  open  to  the  air,  insures  atmospheric  pressure  on  the  outer 
surface  of  the  reagent.  This  tube  serves  to  introduce  the  various  reagents 
for  absorbing  the  gases  to  be  determined.  The  lower  ends  of  both  cham- 
bers project  through  holes  in  the  glass  bottom  of  the  tank,  the  same  pre- 
cautions for  water-tight  closure  observed  in  the  case  of  the  pipettes  A  and 
B  being  also  here  taken. 

REAGENTS   USED. 

The  solution  for  absorbing  carbon  dioxide. — The  solution  for  absorbing 
the  carbon  dioxide  is  prepared  by  dissolving  2400  grams  of  stick  potassium 
hydroxide  in  1750  c.  c.  of  water.  After  the  solution  becomes  cold  it  is 
decanted  to  remove  all  sediment,  and  the  reservoir  C  is  filled  through  the 
tube  at  the  top.  This  is  best  accomplished  by  inserting  a  20  cm.  length 
of  small-sized  glass  tubing  in  the  open  tube  and  attaching  a  funnel  to  it 
by  means  of  a  short  bit  of  rubber  tubing.  This  elongated  funnel  con- 
ducts the  reagent  well  down  into  the  chamber  and  avoids  choking  the 
passage  with  the  somewhat  viscous  liquid.  The  level  of  the  liquid  inside 
and  out  should  be  essentially  the  same,  the  usual  height  being  shown  in 


80  Composition  of  the  Atmosphere 

fig.  1.  Care  should  be  taken  to  prevent  dust  from  entering  the  tube  or 
liquid,  as  it  is  liable  to  accumulate  on  the  inside  of  the  reservoir  and  ulti- 
mately cause  difficulty  in  reading  the  exact  height  of  the  liquid  in  the 
capillary  tubing. 

The  solution  for  absorbing  oxygen. — Shortly  after  Liebig  announced  his 
discovery  of  the  fact  that  potassium  pyrogallate  absorbed  oxygen  quanti- 
tatively, the  criticism  was  raised  by  Calvert,  Boussingault,  and  Cloez* 
that  potassium  pyrogallate,  when  reacting  with  oxygen,  gave  rise  to  the 
formation  of  a  certain  amount  of  carbon  monoxide,  the  evolution  of  this 
gas  naturally  vitiating  the  results  obtained  by  this  method  of  analysis. 
Several  years  later  a  further  caution  was  published  by  Hempel  to  the 
effect  that  one  should  not  use  potassium  hydroxide  ^'purified  by  alcohol' ' 
in  the  preparation  of  the  potassium  pyrogallate.  ^  In  this  defense  of  the 
use  of  the  pyrogallate  solution,  he  also  pointed  out  that  if  proper  attention 
was  given  to  the  concentration  of  the  solution  there  need  be  no  fear  of 
the  evolution  of  carbon  monoxide. 

When  the  formulas  for  preparing  this  solution  are  examined,  it  is 
found  that  the  main  differences  noted  are  in  the  proportion  of  water  pres- 
ent. When  "a  60  per  cent  solution  of  caustic  potash"  is  stated,  one  im- 
mediately has  to  determine  what  is  meant  by  *'a  60  per  cent  solution." 
Even  when  the  weight  of  potassium  hydroxide  is  given  in  the  formula, 
difficulty  is  experienced  owing  to  the  differences  in  water-content  of  the 
substance,  stick  potassium  hydroxide  frequently  containing  as  much  as 
25  per  cent  of  water.  Haldane's  formula  alone  obviates  this  difficulty, 
as  he  requires  a  fully  saturated  solution  of  potassium  hydroxide  with 
a  specific  gravity  of  1.55.  Earlier  experience  with  Haldane's  formula, 
however,  showed  that  with  a  low  room-temperature  the  material  solidi- 
fied; and  with  so  delicate  an  apparatus  as  that  of  Sond^n  it  seemed  un- 
desirable to  introduce  a  reagent  that  might  solidify  and  possibly  burst 
the  glass  container. 

Since  the  prime  object  of  this  research  was  a  comparative  study  of  the 
oxygen  content  of  the  air,  and  since  certain  fundamental  defects  in  the 
apparatus  prevented  deductions  regarding  the  exact  absolute  value,  we 
modified  slightly  Haldane's  solution  as  follows: 

A  solution  of  potassium  hydroxide  was  prepared  by  dissolving  500 
grams  of  stick  potassium  hydroxide,  not  purified  by  alcohol,  in  250  c.  c. 
of  water.  Usually  the  specific  gravity  of  the  resulting  solution  was  1.55. 
During  the  progress  of  this  research,  several  shipments  of  stick  potassium 
hydroxide  were  used,  and  the  varying  water-content  of  the  chemical  is 
shown  by  the  fact  that  it  was  frequently  necessary  to  add  more  potassium 
hydroxide  to  bring  the  solution  to  the  desired  density.  To  135  c.  c.  of  this 
saturated  solution  was  added  a  solution  of  15  grams  of  pjo-ogallic  acid 

1  Calvert,  Comptes  rendus,  1863,  57,  p.  873;  Cloez,  Comptes  rendus,  1863,  57,  p.  875; 
Boussingault,  Comptes  rendus,  1863,  57,  p.  885. 

2  Hempel,  Bericht«  der  deutschen  chemischen  Gesellschaft,  1887,  20,  p.  1865. 


Apparatus  and  Methods  81 

in  15  c.  c.  of  distilled  water.  By  means  of  the  funnel  and  tube,  the  mixed 
solutions  were  then  carefully  introduced  into  chamber  D.  One  such  charge 
of  potassium  pyrogallate  was  found  to  be  sufficient  to  make  approximately 
30  air-analyses. 

This  solution  takes  up  oxygen  rapidly  and  has  a  high  absorptive  ca- 
pacity. It  has  been  assumed  that  since  the  solution  was  so  much  more 
concentrated  than  Hempel's,  his  assertion  that  no  carbon  monoxide  was 
developed  with  his  weaker  solutions  held  true  in  this  case  also,  particu- 
larly as  Haldane  states  that  with  his  extremely  concentrated  solution  no 
traces  of  carbon  monoxide  are  found.  Furthermore,  certain  evidence 
here  presented  seems  to  support  this  view.  When  a  known  sample  of  air 
is  analyzed  a  number  of  times,  the  percentage  of  oxygen  at  the  beginning 
of  the  series  does  not  differ  from  that  found  at  the  end,  even  when  as  many 
as  30  analyses  are  made  with  the  one  charge  of  potassium  pyrogallate. 
It  seems  reasonable  to  suppose  that  if  carbon  monoxide  were  formed,  a 
somewhat  different  amount  would  be  produced  after  the  first,  second,  or 
third  analysis  than  after  the  twenty-eighth  or  twenty-ninth.  On  the 
other  hand,  it  is  not  impossible  that  in  the  production  of  carbon  monoxide 
there  may  be  an  extremely  small  quantitative  relationship  between  the 
oxygen  absorbed  and  the  disintegration  of  the  pyrogallic  acid,  so  that 
the  carbon  monoxide  given  off  may  remain  strictly  proportional  to  the 
amount  of  oxygen  consumed.  Since  in  each  of  these  analyses  exactly  the 
same  amount  of  oxygen  is  absorbed,  there  still  may  be  a  slight  constant 
factor  present;  consequently,  it  is  necessary  to  take  into  consideration  the 
fact  that  in  all  of  these  analyses  there  may  be  traces  of  carbon  monoxide 
produced.  In  that  case  the  tendency  would  be  to  make  the  percentage 
of  oxygen  slightly  too  small.  Although  throughout  the  whole  research 
a  slightly  modified  Haldane  solution  was  used,  subsequent  experiments 
with  the  Haldane  formula  show  a  somewhat  larger  oxygen  percentage. 
This  increased  percentage  may  be  due  to  two  causes:  (1)  the  actual  ab- 
sorption of  more  oxygen,  or  what  is  more  probable,  (2)  the  formation  of 
less  or  no  carbon  monoxide.  It  remains  a  fact,  nevertheless,  that  the 
solution  as  used  is  without  question  suitable  for  a  comparative  study  of 
the  oxygen  percentage  of  the  atmosphere. 


82  Composition  of  the  Atmosphere 

PLAN  AND  METHODS  OF  RESEARCH. 

The  report  of  the  research  carried  out  with  this  apparatus  may  be  sub- 
divided into  several  parts  as  follows: 

(1)  The  main  study  of  the  comparative  oxygen-content  of  uncontami- 
nated  outdoor  air  under  all  conditions  as  to  wind  direction  and  strength, 
temperature,  cloud  formation,  barometer,  and  weather,  including  rain, 
snow,  fog,  and  mist. 

(2)  A  study  of  the  influence  of  the  temperature  of  the  reagent  upon 
its  absorptive  power. 

(3)  An  examination  of  samples  of  air  collected  on  the  North  Atlantic 
Ocean  between  Montreal  and  Liverpool,  and  between  Genoa  and  Boston. 

(4)  Analyses  of  air  obtained  from  the  top  of  Pike's  Peak. 

(5)  Analyses  of  air  taken  in  the  crowded  streets  of  Boston. 

(6)  Analyses  of  air  taken  in  the  Boston  and  New  York  subways. 

(7)  An  experimental  research  with  various  absorbents  for  oxygen. 
Before  proceeding  to  a  description  of  the  routine  of  air-analysis  with 

this  apparatus,  a  discussion  of  the  method  of  procuring  samples  of  un- 
contaminated  outdoor  air  is  advisable.  By  far  the  greater  number  of 
analyses  were  made  of  air  collected  near  the  laboratory,  and  a  permanent 
installation  was  made  to  secure  convenient  and  accurate  sampling  of  air. 
It  is  unnecessary  at  this  point  to  describe  the  methods  of  sampling  em- 
ployed when  samples  were  taken  at  some  distance  from  the  laboratory. 

METHOD  OF  COLLECTING  OUTDOOR  AIR. 

As  the  laboratory  is  located  near  a  large  power-house,  it  was  feared 
that  in  spite  of  all  precautions  there  would  be  a  contamination  of  the  at- 
mosphere due  to  the  products  of  combustion  from  the  large  furnaces.  On 
the  other  hand,  as  the  prevailing  winds  are  from  the  southwest  and  the 
power-house  is  north  of  the  laboratory,  it  seemed  probable  that  during 
the  prevailing  winds  the  contamination  should  not  be  perceptible.  In 
order  to  provide  for  a  possible  variation  in  composition  on  two  sides  of 
the  building,  arrangements  were  made  for  taking  samples  on  both  the 
east  and  west  sides.     The  sampling  arrangements  are  as  follows: 

A  standard  J/g-inch  brass  pipe  (7  mm.  internal  and  10  mm.  external 
diameter)  was  extended  out  from  the  west  wall  of  the  laboratory,  4.8 
meters  from  the  ground  and  at  a  distance  of  2.2  meters  from  the  wall. 
The  end  was  pointed  downward  so  as  to  prevent  clogging  by  water,  ice, 
or  dirt.  This  pipe  was  then  brought  into  the  laboratory,  conducted  to 
the  sink  near  the  gas-analysis  apparatus,  and  a  water-suction  pump  so 
connected  as  to  suck  continuously  a  current  of  air  from  outdoors  through 
the  pipe.  The  intake  tube  of  the  gas-analysis  apparatus  was  attached 
to  the  air-pipe,  so  that  it  was  possible  to  have  a  continuous  stream  of  fresh 
outdoor  air  passing  by  the  analysis  apparatus.  Similarly,  a  second  pipe 
was  carried  out  from  the  east  side  of  the  building  at  the  same  distance 
from  the  ground  as  the  pipe  on  the  west  side.     This  pipe  was  also  con- 


Comparative  Air-Analyses  83 

nected  with  the  gas-analysis  apparatus,  so  that  by  turning  a  valve  the 
water-suction  pump  could  be  connected  with  either  the  west  or  the  east 
pipe  and  fresh  outdoor  air  drawn  from  either  side  of  the  building  at  will. 
In  all  analyses  care  was  taken  to  have  the  suction  pump  in  full  operation 
for  several  minutes  before  taking  the  sample,  thus  insuring  a  complete 
sweeping  out  of  the  pipe  by  fresh  outdoor  air.  With  all  analyses  simul- 
taneous records  have  been  made  of  the  weather,  the  direction  and  strength 
of  the  wind,  the  outdoor  temperature,  and  the  barometer. 

METHOD    OF   USING   THE   APPARATUS   AND   RESULTS   OBTAINED. 

The  best  procedure  in  the  use  of  this  apparatus  is  by  no  means  obvious 
from  an  inspection  of  its  construction;  furthermore,  as  errors  appeared  in 
the  technique  and  in  the  apparatus,  the  routine  has  been  altered  funda- 
mentally on  several  occasions.  Inasmuch  as  the  results  first  obtained 
are  so  completely  in  harmony  with  many  of  those  of  the  earlier  inves- 
tigators, it  seems  advisable  to  give  our  entire  series  here,  even  though  we 
know  that  the  results  of  the  first  two  years  are  open  to  objection,  owing 
to  slight  errors  which  disappeared  as  the  routine  became  more  perfected. 

While  the  investigation  was  started  primarily  to  study  the  oxygen- 
content  of  the  outdoor  air,  it  was  necessary  to  determine  beforehand  the 
carbon  dioxide,  since  an  alkaline  absorbent  for  oxygen  was  employed; 
hence  practically  all  the  analyses  are  accompanied  by  simultaneous  de- 
terminations of  the  carbon  dioxide  in  the  air.  In  the  especially  exact  ap- 
paratus designed  by  Sonden  and  Pettersson,  the  carbon  dioxide  is  de- 
termined to  the  third  or  fourth  significant  figure,  but  as  the  amounts  of 
carbon  dioxide  that  were  to  be  used  in  our  apparatus  might  at  times  reach 
1  per  cent,  it  was  impossible  to  secure  this  degree  of  fineness  in  the  cali- 
bration of  the  carbon-dioxide  pipette,  hence  readings  can  be  taken  only 
to  one-thousandth  of  1  per  cent.  Consequently,  since  other  methods  are 
better  adapted  for  securing  accurate  carbon-dioxide  determinations,  little 
stress  has  been  laid  upon  the  determinations  made  in  connection  with 
this  research,  although  they  are  probably  accurate  to  within  0.002  in  all 
cases.  At  one  time  during  the  research  it  was  found  that  the  potassium 
hydroxide  reagent  chamber  C  was  broken,  so  it  became  temporarily 
necessary  to  absorb  simultaneously  the  carbon  dioxide  and  oxygen;  hence 
for  a  short  period  the  percentages  represent  the  percentage  of  oxygen 
plus  that  of  carbon  dioxide.  As  soon  as  possible  the  reagent  chamber 
was  repaired  and  the  research  was  then  continued  in  the  usual  way.        ., 

FIRST  ROUTINE,   AND  RESULTS   OBTAINED. 

The  earlier  results  in  this  series  are  especially  interesting  as  indicating 
how  it  is  possible  by  constancy  in  routine  to  secure  duplicate  results  on 
practically  all  samples.  Furthermore,  it  is  interesting  to  note  that  if  the 
research  had  been  discontinued  at  the  end  of  the  second  year,  the  results 
could  easily  have  been  taken  as  verifying  completely  those  of  the  earlier 
investigators,  vf\tb  showed  that  fluctuations  in  the  oxygen  content  of  the 
atmosphere  are  to  be  expected,  slight  though  they  may  be. 


84  Composition  of  the  Atmosphere 

The  apparatus  described  was  first  set  in  order  in  the  latter  part  of 
February  1909.  After  considerable  preliminary  experimenting  with  room 
air  and  with  air  from  a  respiration  chamber,  a  series  of  analyses  of  out- 
door air  was  begun  on  April  5,  1909.  The  first  routine  employed  for  de- 
termining the  carbon  dioxide  and  oxygen  is  as  follows: 

Outline  of  first  routine. — It  is  necessary  in  the  first  place  to  make  sure 
that  all  the  capillary  tubes  communicating  with  the  different  reservoirs 
are  filled  with  nitrogen  and  not  with  air.  For  this  purpose  a  blank  analy- 
sis is  made  in  which  quantitative  accuracy  is  not  required.  In  making 
this  analysis,  the  air  in  the  apparatus  is  first  passed  into  the  potassium 
pyrogallate  several  times  until  thorough  absorption  of  both  carbon  dioxide 
and  oxygen  is  assured;  it  is  then  allowed  to  flow  into  the  potassium  hy- 
droxide and  repeatedly  drawn  back  and  forth  by  means  of  the  leveling 
bulb  E  until  the  air  in  all  of  the  capillary  tubes  is  replaced  by  nitrogen, 
the  air  being  intermittently  sent  into  the  potassium  pyrogallate  to  absorb 
the  slight  traces  of  oxygen  picked  up  in  its  passage  through  the  capillary 
tubing.  The  level  of  the  potassium  hydroxide  in  the  capillary  tube  is 
then  brought  to  a  definite  point  by  lowering  the  mercury  in  the  pipette 
By  the  final  adjustment  being  made  by  the  screw-cock  N ;  a  decreased  ten- 
sion is  thus  produced  which  raises  the  reagent  to  the  desired  mark.  When 
this  point  is  reached  the  stop-cock  h  is  turned  180  degrees  to  communi- 
cate with  the  chamber  D.  We  now  have  pure  nitrogen  in  the  capillary 
tube  leading  from  the  potassium  hydroxide  reservoir  to  the  stop-cock  h. 
Since  all  the  other  capillaries  are  likewise  filled  with  pure  nitrogen,  pressure 
is  applied  at  screw-cock  N  to  bring  the  potassium-pyrogallate  solution  to 
a  definite  mark  on  the  capillary  tube  before  shutting  off  the  stop-cock  6. 
After  turning  stop-cock  a  180  degrees,  the  excess  of  nitrogen  is  then  ex- 
pelled through  the  stop-cock  d  by  means  of  the  leveling  bulb  E. 

Between  the  stop-cock  d  and  the  pipe  coming  from  the  outside  of  the 
laboratory  is  a  three-way  stop-cock,  one  side  of  which  is  opened  to  the 
room  air.  When  taking  the  sample  of  air  for  analysis,  this  three-way 
stop-cock  is  so  turned  as  to  allow  direct  communication  between  the  gas- 
analysis  apparatus  and  the  sampling  pipe  through  which  a  suction  pump 
draws  a  current  of  outside  air.  Under  these  conditions,  by  lowering 
the  mercury  reservoir  E,  mercury  runs  out  of  the  pipette  B  and  air  is 
drawn  in  through  the  capillary  stop-cock  d.  The  leveling  bulb  is  again 
raised  and  the  pipette  repeatedly  swept  out  by  pure  air.  When  a 
thorough  and  accurate  sweeping  out  of  the  nitrogen  is  insured  and  the 
pipette  is  full  of  uncontaminated  outdoor  air,  the  sample  is  ready  to  be 
measured.  The  mercury  is  finally  lowered  to  a  mark  somewhat  below 
the  zero  mark  on  the  pipette.  The  suction  pump  is  then  stopped  and  the 
three-way  stop-cock  between  the  gas-analysis  apparatus  and  the  sample 
pipe  (not  shown  in  either  figure)  turned  so  as  to  communicate  directly 
with  the  room  air.  By  raising  the  level  of  the  mercury  to  the  zero  mark 
on  the  bottom  of  the  pipette  B,  a  slight  amount  of  air  is  expelled  and  the 


Comparative  Air-Analyses  85 

level  is  set  exactly  at  zero  by  the  fine  adjusting  screw  N.  The  stop- 
cock c  is  then  turned  so  that  the  compensating  pipette  A  communicates 
directly  with  the  room  air,  and  by  means  of  the  finely  threaded  adjust- 
ment screw  P,  the  level  of  the  mercury  in  A  is  also  brought  to  the  zero 
point.  Under  these  conditions,  therefore,  the  gas  in  both  pipettes  is  at 
the  same  temperature  and  pressure.  To  test  this  the  stop-cocks  c  and  d 
are  simultaneously  and  cautiously  turned  and  the  two  reservoirs  A  and  B 
placed  in  communication  with  the  manometer;  there  should  be  no  move- 
ment of  the  oil-drop  on  the  scale,  thus  indicating  constancy  in  tempera- 
ture and  barometric  conditions.  The  stop-cocks  c  and  d  are  again  turned 
so  as  to  cut  off  the  manometer,  and  the  sample  is  ready  for  analysis. 

The  gas  is  first  sent  into  the  potassium  hydroxide  to  absorb  the  carbon 
dioxide.  This  is  done  by  turning  the  stop-cock  a  180  degrees  and  subse- 
quently turning  stop-cock  b  so  as  to  allow  the  air  to  enter  the  capillary 
leading  to  C.  It  is  next  slowly  passed  into  the  potassium  hydroxide 
twice  by  raising  and  lowering  the  mercury  leveling-bulb  E.  The  air  is 
then  drawn  back  into  B,  the  level  of  the  reagent  is  again  set,  and  the  level 
of  the  mercury  in  the  pipette  B  is  brought  down  to  the  original  zero-mark. 
Under  these  conditions  there  is  a  slightly  diminished  pressure  in  the  pi- 
pette B,  due  to  the  decrease  in  volume  it  has  sustained  by  the  absorption 
of  the  carbon  dioxide;  consequently,  before  connecting  pipette  A  to  the 
manometer,  the  pressure  of  the  air  inside  A,  which  is  now  acting  as  the 
compensating  vessel,  must  be  somewhat  decreased.  This  decrease  in 
pressure  is  obtained  by  lowering  the  mercury  column  by  an  amount 
which  is  estimated  as  being  approximately  the  percentage  of  carbon 
dioxide  in  the  air.  For  ordinary  outdoor  air  this  is  not  far  from  0.03  per 
cent.  Under  these  conditions,  therefore,  when  the  stop-cocks  c  and  d 
communicating  with  the  manometer  are  turned  there  will  be  a  slight  de- 
flection of  the  oil  globule  on  the  scale  to  the  right  or  to  the  left,  if  the 
pressure  is  greater  in  either  A  or  B.  For  example,  if  the  movement  of  the 
petroleum  globule  is  toward  the  right,  it  signifies  that  the  pressure  in  the 
pipette  A  is  greater;  accordingly,  it  is  necessary  to  lower  the  mercury  in  A 
until  the  petroleum  drop  is  exactly  in  the  center.  When  the  manometer 
shows  that  the  temperature  and  pressure  are  the  same  in  both  pipettes, 
a  direct  reading  of  the  percentage  of  carbon  dioxide  may  be  obtained  by 
noting  the  fall  of  the  mercury  level  in  A. 

To  obtain  a  second  reading,  the  manometer  stop-cocks  are  again  turned 
90  degrees,  and  then,  by  properly  turning  the  stop-cocks  a  and  b,  the  air 
is  once  more  sent  into  the  potassium-hydroxide  solution.  The  level  of 
the  reagent  is  again  set  and  after  communicating  with  the  manometer  the 
reading  is  taken.  The  second  reading  is  usually  identical  with  the  first, 
as  the  amount  of  carbon  dioxide  to  be  absorbed  is  extremely  small. 

At  this  point  the  carbon  dioxide  has  been  completely  removed  from  the 
gas  in  the  apparatus,  but  the  capillary  tube  between  the  stop-cock  b  and 
the  level  of  the  potassium  hydroxide  now  contains  air  instead  of  nitrogen. 


86 


Composition  of  the  Atmospheke 


By  properly  adjusting  the  stop-cocks  a  and  b  the  air  sample  is  slowly  sent 
into  the  potassium  pyrogallate  pipette  and  allowed  to  remain  one  minute. 
After  being  drawn  back  and  forth  twice,  it  is  left  over  the  potassium  py- 
rogallate for  another  minute,  again  drawn  back  and  forth  twice,  next  sent 
to  the  potassium  hydroxide  pipette  three  times,  and  finally  into  the  po- 
tassium pyrogallate  three  times.  When  the  air  leaves  each  separate 
pipette  for  the  last  time  the  level  for  the  potassium  hydroxide  and  the 
potassium  pyrogallate  respectively  are  exactly  set.  Under  these  con- 
ditions there  will  be  a  marked  difference  in  the  level  of  the  mercury 
in  the  pipette  B,  owing  to  the  absorption  of  the  oxygen.  In  adjusting 
the  level  of  the  mercury  in  this  pipette,  instead  of  drawing  it  to  the  zero 
point,  it  is  brought  back  until  it  remains  in  the  upper  part  of  the  grad- 
uated portion  of  the  pipette.  If  outdoor  air  is  being  analyzed,  and  the 
composition  is  known  with  considerable  exactness,  it  can  usually  be  set 
not  far  from  20.9.  Then  by  communicating  with  the  manometer,  and 
noting  whether  the  oil  index  moves  to  the  right  or  to  the  left,  the  mercury 
in  the  pipette  B  may  be  raised  or  lowered  as  necessary,  without  altering 
in  any  way  the  level  of  the  mercury  in  the  pipette  A,  until  a  position  is 
finally  obtained  which  indicates  constancy  in  temperature  and  pressure 
conditions  exactly  like  those  of  the  air  in  the  compensating  pipette  A .  A 
reading  of  the  percentage  of  oxygen  is  now  taken.  After  turning  the 
manometer  stop-cocks,  the  air  is  sent  into  the  potassium  pyrogallate 
three  times  after  each  reading,  and  readings  are  taken  until  they  agree 
within  0.002  of  each  other. 

The  routine  outlined  was  followed  with  practically  no  modification 
from  April  5  up  to  Nov.  3,  1909.  The  details  of  an  analysis  made  on  April 
5  at  11^45"  a.  m.  and  carried  out  with  this  routine  are  given  in  table  50. 

Table  50. — Results  obtained  on  sample  of  outdoor  air  with 
first  routine,  April  5,  1909,  11^U5^  a.  m. 


Reading. 

Carbon 
dioxide. 

Oxygen. 

First     

Second  

Third 

p.ct. 

0.029 
0.031 

V.ct. 

20.893 
20.911 
20.923 
20.929 
20.929 

Fourth  

Fifth 

Results  with  first  routine, — The  total  results  for  the  first  stage  in  the  de- 
velopment of  this  method,  namely,  from  April  5  until  November  3, 1909,  are 
given  in  table  51.  It  should  he  noted  that  these  results  are  not  of  selected 
analyses,  hut  include  the  records  of  every  analysis  made  during  this  time, 
including  hoth  good  and  had.  In  the  analyses  from  May  28  to  June  3 
it  was  necessary  to  absorb  carbon  dioxide  and  oxygen  simultaneously, 
owing  to  the  fracture  of  the  potassium-hydroxide  chamber  C  previously 
referred  to.  An  examination  of  the  data  shows  that  on  the  whole  there 
is  no  material  difference  between  the  analyses  made  of  air  taken  from  the 


Comparative  Air-Analyses 


87 


Table  51. — AncUyaes  of  outdoor  air  made  at  the  Nutrition  Laboratory.^ 

Series  I. 

Date. 

Time. 

Tem- 
pera- 
ture. 

Ba- 
rom- 
eter. 

Wind. 

Weather. 

West  Bide. 

East  side. 

Carbon 
diox- 
ide. 

Oxy- 
gen. 

Car- 
bon 
diox- 
ide. 

Oxy- 
gen. 

1909. 
Apr.    5 

Apr.    6 
Apr.     8 

Apr.    9 

Apr.  10 

Apr .  12 

Apr.  17 

Apr.  19 
Apr.  20 

Apr.  21 
Apr.  22 
Apr.  23 
Apr.  28 

Apr.  29 
Apr.  30 

May    1 
May    3 
May    8 

May  10 
May  12 
May  13 
May  14 
May  17 
May  18 
May  20 
May  21 

May  22 
May  22 
May  24 
May  25 
May  26 
May  27 
May  28 
May  29 
June    1 
June    2 
June    3 
Oct.  18 

Oct.  19 

Ilh45ma.m. 
4  00  p.m. 

16.4 
11.0 

8.3 

6.8 

11.0 

13.7 

12.1 

23.7 

8.5 

6.8 
14.0 
14.7 
10.9 

13.3 
2.7 

6.1 
11.0 

mm. 
764.10 

761.35 
758.50 

756.50 

760.65 

774.50 

767.50 
767.15 
752.50 
765.35 

769.90 
756.30 
760.30 
760.00 

770.50 
763.65 

753.50 
766.60 

Light  SW . .  . . 

E 

SW.  gale   .... 

SE 

Pleasant  

....Do 

....Do 

Rain 

p.ct. 

0.031 
.032 
.028 
.026 
.029 
.030 
.027 
.030 
.027 
.029 
.030 
.029 
.030 
031 

p.ct. 
20.929 
20.921 
20.920 
20.921 
20.922 
20.918 

p.ct. 
0.029 
.02S 
.029 
.028 

20.920 
20.941 
20.880 

20  Q21 

11  00  a.in. 

11  00  a.m. 
5  00  p.m. 

10  00  a.m. 

12  00  noon 

.026  1  20.931 

0.^0  1  20  Q21 

W 

20.919  .030  1  20.919 

20.920  .031  I  20.920 

20.921  1  .029    20.920 
20  920   >   -0.^0  !  20  Q21 

s 

Pleasant 

s 

20.920 
20.901 
20.911 

20  Q21 

.029 

*.030 
.032 

.029 

'.030 
.030 
.030 
.032 

'.029 

'.osi 

.028 
.034 
.032 
.028 
.032 
.030 
.029 
.029 

.030 

20.921 
20.931 
20.902 

20.920 

20.922 
20.920 
20.920 
20.902 

2i6'.9i9 

20.920 
20.921 
20.920 
20.920 
20.910 
20.918 
20.920 
20.919 
20.919 

20  010 

s 

SW 

NE 

.032  j  20.921 
.030  I  20.922 
.031    20.020 

10  00  a.m. 

E 

W 

Pleasant 

.031 
.031 
.032 
.032 
.030 

20.921 
20.920 
20.901 
20.902 
20  Q1Q 

N 

11  00  a.m. 

W 

Pleasant  

....Do 

Rain 

Rain 

Pleasant  .... 

N 

E 

.030    20.921 
.032    20.920 
.030  1  20.921 

028  '  5!0  Q5>9! 

N 

SW 

.028 

.028 
.029 
.029 
.031 
.028 

20.920 

20.9ii 
20.919 
20.921 
20.920 
20Q20 

23.3 
21.9 
23.2 
26.0 
10.1 

is.o 

13.9 

8.5 

5.5 

28.0 

19.0 

3i.'2 
14.3 
12.2 

2i.'6 
23.7 

760.50 
764.85 
764.00 
757.75 
761.00 

SW 

W 

Pleasant 

Do 

SW 

W     ..      . . 

E 

Rain 

.030    20.912 
.029  j  20.911 
.029  !  20.901 
.029  1  20.921 
.031  !  20.902 
.029  t  20.902 
.028  ;  20.922 
.030    20.920 
.029  1  20.921 
.031  1  20.920 

20.950 

20.950 

20.949 

20.940 

20.949 
.031  1  20.920 
.032    20.919 
.028    20.919 

769.65 
770.15 

766.00 
764.00 
756.70 
762.85 
769.10 
766.70 
756.70 
752.60 
762.00 
764.30 
760.55 

E 

Pleasant 

E 

.028     20  920    1 

a.m 

3h00"p.m... 

NE 

NE.  strong  .  . . 

Stormy 

".630 

■.028 
.029 
.030 
.029 

20.962 

20.920 
20.920 
20.919 
20.920 

W ... 

Pleasant  .... 

NW 

NW 



Pleasant 

S.    .    . 

N 

N 

NW 

Pleasant  .... 
Cloudy 

SE.     .      .    . 

SW 

a.m 

p.m 



771.45 

NW 

Pleasant  .... 

'  In  all  of  the  analyses  of  air  made  in  this  research,  the  temperature  of  the  water  bath  varied  from  17* 
to  21°  C.  and  was  usually  not  far  from  19°  or  20°  C.  Subsequent  experiments  (see  p.  97)  showed  that  tem- 
perature variations  do  not  materially  influence  the  results. 

'  In  this  analysis  the  mercury  in  the  compensation  tube  was  inadvertently  brought  back  to  0  after  the 
carbon  dioxide  had  been  absorbed. 

west  side  of  the  building  and  those  from  the  east  side.  In  view  of  these 
results  it  was  not  considered  necessary  to  draw  samples  from  both  sides  of 
the  building,  and  only  those  drawn  from  the  wxst  side  were  analyzed  for 
the  remainder  of  the  research.  Aside  from  certain  values  which  are  ob- 
viously erroneous,  it  would  appear  that  the  average  percentage  of  oxygen 
was  not  far  from  20.92,  as  indicated  by  this  technique  and  under  these  con- 
ditions. The  fluctuations  in  the  percentage  of  carbon  dioxide  are  those 
commonly  experienced  and  represent  nothing  unusual,  save  that  on 
days  when  the  wind  was  blowing  directly  from  the  thickly  settled  por- 
tion of  the  city  a  much  higher  carbon-dioxide  content  than  at  other  times 


88  Composition  of  the  Atmosphere 

would  be  expected  instead  of  the  constancy  indicated.  The  laboratory- 
is  so  situated  that  the  wind  from  the  southwest  would  come  from  the 
more  residential  portion  of  the  city,  while  the  wind  from  the  northeast 
and  east  would  come  from  the  business  and  factory  part  of  the  city.  The 
power-house  of  the  Harvard  Medical  School  is  located  exactly  north  (100 
meters)  from  the  laboratory,  but  aside  from  this,  no  large  factories  or 
other  smoke-producing  buildings  are  nearer  than  600  meters. 

Errors  in  first  routine. — In  October  1909  it  was  found  that  if  the  trans- 
fer of  gas  from  pipette  B  to  the  potassium  pyrogallate  was  continued  for 
some  time,  there  was  usually  a  steady,  though  slight,  increase  in  the  per- 
centage of  oxygen,  this  increase  amounting  to  from  0.001  to  0.002  per  cent 
for  each  repetition  of  the  routine.  Furthermore,  the  increase  continued 
until  the  percentage  of  oxygen  had  risen  from  20.92  to  21  and  over,  when 
it  could  no  longer  be  read  accurately,  as  the  graduations  extended  no 
farther.  It  was  believed  at  that  time  that  this  increase  was  due  to  the 
distillation  of  water  from  the  pipette  B  over  into  the  solution  of  potassium 
hydroxide.  The  theory  was  that  the  strong  alkali  had  a  tension  of  aque- 
ous vapor  considerably  less  than  that  of  water,  and  that  each  time  that 
the  air  was  sent  over  into  the  potassium  pyrogallate  it  carried  with  it  a 
slight  amount  of  moisture;  this  moisture  was  retained  by  the  strong 
alkali  until  all  the  water  was  gradually  distilled  over. 

SECOND  ROUTINE,   AND   RESULTS  OBTAINED. 

Since  it  seemed  desirable  to  minimize  as  much  as  possible  the  trans- 
fers of  air  from  the  measuring  pipette  into  the  strong  alkali,  the  first  rou- 
tine was  modified  somewhat,  and  a  second  routine  adopted  on  November 
3, 1909.     The  following  changes  were  made  in  the  method : 

The  absorption  of  the  carbon  dioxide  was  unchanged,  the  variation 
in  the  routine  being  chiefly  in  the  determination  of  oxygen.  After  the 
carbon  dioxide  was  absorbed,  the  gas  was  sent  into  the  potassium  pyro- 
gallate and  allowed  to  remain  for  10  minutes.  It  was  then  withdrawn  and 
after  being  sent  into  the  potassium  hydroxide  was  again  returned  to  the 
potassium  pyrogallate  and  allowed  to  remain  5  minutes.  Then  the  first 
reading  was  taken.  This  procedure,  i.e.,  once  into  the  potassium  hydrox- 
ide and  a  5-minute  sojourn  over  the  potassium  pyrogallate,  was  carried 
out  three  times,  readings  being  taken  as  each  routine  was  concluded. 

Results  loith  second  routine. — The  second  routine  was  followed  almost 
without  change  from  November  3,  1909,  until  February  15,  1911,  sam- 
ples being  taken  only  on  the  west  side  of  the  laboratory.  A  sample  analy- 
sis made  on  November  4,  1909,  is  given  in  table  52.  The  detailed  results 
for  this  series  of  analyses  are  given  in  table  53,  in  which  are  incorporated, 
likewise,  the  temperature  of  the  outdoor  air,  the  barometer,  and  data 
regarding  the  wind  and  weather,  as  well  as  the  times  at  which  the  analyses 
were  made.  These  analyses  were  continued  over  a  period  of  more  than  a 
year,  the  summer  months  only  being  excepted. 


Comparative  Air-Analyses 


89 


Table  52. — Results  obtained  on  sample  of  outdoor  air  with 
second  routine,  November  4,  iqoq,  q^jo'^  a.  m. 


Reading. 

Carbon 
dioxide. 

Oxygen. 

First  

V.ct. 

0.035 
0.036 

V.ct. 
20.888 
20.909 
20.910 

Second  

Third 

Table  53. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory. 

[All  samples  were  taken  from  the  west  side  of  the  laboratory.] 


Series  2. 


Date. 

Time. 

Temper- 
ature. 

Barom- 
eter. 

Wind. 

Weather. 

Carbon 
dioxide. 

Oxygen, 

1909. 
Nov.    4 
Nov     5 

Nov.    6 

Nov.    8 

Nov.  10 

Nov.  11 

Nov.  12 

Nov.  13 

Nov.  15 

Nov.  16 

Nov.  17 

Nov.  18 

Nov.  22 

Nov.  23 

Nov.  24 
Nov.  29 
Dec.     9 
Dec.  21 
Dec.  22 

Dec.  27 

Dec.  28 

Dec.  29 

Dec.  30 

Dec,  31 

1910 
Jan.      1 

Jan.     3 
Jan.     4 
Jan.     5 
Jan.     6 

Jan.     6 

Jan.     7 

Jan.     7 
Jan.     8 

9hl0">a.m. 
3  12  p.m. 

10  00  a.m. 
9  00  a.m. 

11  25  a.m. 
9  16  a.m. 
8  47  a.m. 
8  56  a.m. 
8  57  a.m. 

8  34  a.m. 
10  34  a.m. 

9  45  a.m. 
9  14  a.m. 

8  46  a.m, 

3  31  p.m. 

9  37  a.m. 

10  34  a.m. 
9  30  a.m, 

8  32  a.m, 

11  16  a.m. 
2  37  p.m. 

2  52  p.m. 
10  24  a.m. 

9  27  a.m. 
8  57  a.m. 

8  45  a.m. 

8  40  a.m. 

9  21  a.m. 
8  50  a.m. 
8  58  a.m. 

a.m 

p.m 

8h43n'a.m. 

2  49  p.m. 
8  39  a.m. 

.... 
4.0 

8.7 

7.8 

11.7 

17.8 

11.7 

11.7 

6.9 

14.9 

4.8 

6.8 

17.9 

0.0 
3.0 

—  6 
-12 

—  8 

—  3 

1 
—14 
—15 

6 

6 

2 

2 

—  4 

mm. 
753.25 
763.60 

774.95 
779.90 
778.00 
767.05 
775.55 
769.90 
769.90 
751.75 

766.00 
752.50 

762.00 
764.70 
760.00 
760.77 
756.90 

749.00 
749.10 

752.50 
753.00 
755.55 
766.95 

769.65 

761.85 
775.00 
783.30 
761.35 

759.65 

756.00 

758.10 
778.90 

Pleasant  

Cold,  raw 

p.ct. 
0.036 
.029 
.033 
.035 
.035 
.039 
.035 
.034 
.033 
.035 
.034 
.030 
.031 
.035 
.034 
.035 
.033 
.030 
.030 
.030 
.031 
.033 
.034 
.033 
.034 
.029 
.031 

.027 
.031 
.030 
.029 
.031 
.032 

.028 
.031 

029 
.032 
.041 
.043 
.029 
.031 
,028 
.030 

.031 
.030 
.030 
.029 
.032 
.042 
.035 
.034 
.036 
.040 
.032 
.034 
.031 
.031 

20.91b 
20.932 
20.949 
20.942 
20.940 
20.920 
20.9 1^ 
20.920 
20.923 
20.930 
20.930 
20.920 
20.931 
20.930 
20.927 
20.923 
20.922 
20.931 
20.933 
20.921 
20.923 
20.930 
20.930 
20.925 
20.920 
20.922 
20.921 

20.921 
20.923 
20.919 
20.910 
20.900 
20.920 

20.921 
20.921 

20.910 
20.923 
20.903 
20.902 
20.919 
20.922 
20.911 
20.912 

20.913 
20.913 
20.921 
20.921 
20.919 
20.933 
20.932 

20.920 
20.930 
20.929 
20.932 
20.922 

SW 

Cold,  raw 

Pleasant 

Do 

SW 

W 

Very  little,  if  any 

No  wind 

SW.,  very  little  . 
NW 

....Do 

Overcast    

....Do 

Pleasant 

Rain  . . 

Brisk  SW 

Brisk  NW 

SE. 

Overcast    

Rain 

SW 

Overcast;  rained 
night  before, 
sun  out  part  of 
time.i 

Snow.'sleet    

Stormy 

Pleasant  

Pleasant,  sunny 
Sunny,  bright  .  . 

/'Bright,  sunny^ 
)    snow  storm  ( 
<    day  before,  > 
J    about  30  cm.  I 
V.  snow.               J 
Pleasant  

Strong  NE 

NE.      

w 

SW 

NW 

W.    . 

w 

VeryUttle,  SW. 
Light  WNW.    ., 
NW 

Sunny    

w 

Pleasant  

Sunny  

Cloudy 

Bright    

Snowing 

Rain 

SW 

SW 

NW    

W 

SW 

SW 

NW 

....Do 

Heavy  rain 

Pleasant  

...Do 

NW. 

W  

'Below  zero. 


90 


Composition  of  the  Atmosphere 


Table  53. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory.    Series  2.—ConVd. 
[All  samples  were  taken  from  the  west  side  of  the  laboratory.] 


Date. 


1910. 
Jan.   10 
Jan,  17 
Jan.   18 


Jan. 
Jan. 


Jan.   25 


Jan. 
Jan. 


Jan.  28 
Jan.  29 
Jan.   31 


Feb.  1 
Feb.  2 
Feb.     4 


Feb.  5 
Feb.  7 
Feb.  8 
Feb.  11 

Feb.  12 

Feb.  17 

Mar.  21 

Mar.  24 
Apr.  1 
Apr.  4 
Apr.     5 


Apr. 


Apr.  8 

Apr.  11 

Apr.  13 

Apr.  15 

Apr.  18 

Apr.  21 


Apr.  26 

Apr.  28 

Apr.  29 

May    2 
May    3 

May    4 

May    5 

May    6' 
May    6 


May  7 
May  9 
May  10 


May  11 
May  12 
May  13 
May  16 


Time. 


4h00'°p.m. 
3  49  p.m. 
8  54  a.m. 
8  35  a.m. 
3  51  p.m. 
8  36  a.m. 
8  50  a.m. 

8  56  a.m. 

9  00  a.m. 
10  40  a.m. 

9  00  a.m. 


9  54  a.m. 

10  05  a.m. 

3  49  p.m. 


2  32  p.m. 

3  06  p.m. 

2  44  p.m. 

3  40  p.m. 

11  15  a.m. 
8  50  a.m. 
2  40  p.m. 

2  38  p.m. 
8  27  a.m. 

3  50  p.m. 

8  10  a.m. 

9  12  a.m. 

8  36  a.m. 

2  01  p.m. 

9  12  a.m. 

10  22  a.m. 

7  59  a.m. 

8  19  a.m. 

11  48  a.m. 

8  26  a.m. 

9  24  a.m. 

8  42  a.m. 

9  42  a.m. 

2  31  p.m. 

3  35  p.m. 
10  21  a.m. 

8  37  a.m. 

8  45  a.m. 

8  32  a.m. 

9  32  a.m. 
9  07  a.m. 

10  09  a.m. 

8  33  a.m. 

9  31  a.m. 
9  29  a.m. 

12  20  p.m. 

2  39  p.m. 
9  50  a.m. 
8  42  a.m. 

8  15  a.m. 

9  16  a.m. 
10  17  a.m. 

8  28  a.m. 

3  29  p.m. 

10  53  a.m. 
2  35  p.m. 
2  36  p.m. 


Temper- 
ature. 


"C. 

2 

3.0 

5.0 

5.0 

5.0 

3.0 

3.0 

2.0 

3.0 

3.0 

0.0 


3 

0.0 

1.0 


0.0 
-10 

4 
-  4 

0.0 

0.0 

10.0 


13.0 
16.4 
16.0 

19.0 

18.7 
10.2 

"8.i 
10.2 
20.2 
10.9 

16.6 


15.3 

■9.6 

12.0 

10.0 
12.4 

■9.8 

*9!2 


20.5 
15.8 
17.8 


16.8 

14.9 

13.3 
12.9 
16.5 


Barom- 
eter. 


mm. 
774.00 
768.70 
760.00 
759.00 
765.30 
764.00 
760.20 
748.40 
752.85 
743.85 
762.45 


762.05 
765.25 
753.15 


752.65 
765.75 
765.40 
778.00 

747.00 

766.70 

768.75 


767.55 
765.75 
762.85 

751.66 

750.10 
754.50 

761.45 
765.00 
759.00 
766.50 


763.90 

762;66 

765.90 

768.40 
764.90 

764.90 

766!25 

7&0'.66 


760.00 
757.25 
755.85 


755.00 

756.50 

761.90 
761.65 
772.40 


Wind. 


NW 

E 

SE 

NW 

S.W 

Light  NE. 

W 

SE 

SW 

NE 

NW 


NW. 

NW. 
NW. 


Strong  W. .  . 
Strong  NW. 

SW 

SE 


NW. 
NE. 


Light  W. 


NW.  . . . 

SW.    ... 
No  wind 


SW. 


W.. 

NW. 


NW.  ... 
SW.    ... 

W 

No  wind 


SE 


Light  SE . . . 
Strong  NW' 
Light  NW  . 


No  wind  . 
Light  SW 


SE. 
SE. 


SE 

SE 

No  wind 


Weather. 


Pleasant 
Sunny  . . 
Rain  . .  . 
Simny  . . 
Cloudy  . 
...Do.  . 


Pleasant  . 

Cloudy , 

Sunny,  bright, 

Rain 

Cloudy,  light 

snowstorm  night 

before. 

Pleasant 

.  ...  Do 

Snow  in  morning 
sunny  and 
pleasant  at  3^49™ 
p.m. 


Pleasant  ..... 
Not  sunny  . . , 
Cold,  raw  day,  no 

sun. 
Snowing      and 

raining,  raw  day. 
Cold,  raw  day, 

misty. 
Pleasant,    sunny 

and  bright. 

...Do 

...Do 

Cloudy 

...Do 

Sunny  

Slightly  overcast, 

very  warm. 
Very  cloudy  .  . 
Cloudy 


Very  pleasant  . 
Pleasant,  sunny 
Sunny,  bright  . 
Rained  a  little  . 


Pleasant  but  not 
sunny. 


Rainy 


Pleasant,     cool, 

and  windy. 
Very     pleasant; 

sunny. 

Cloudy 

...Do 


NW 

Cloudy 

Light  SW 

Cloudy 

SW 

Very  pleasant: 
sunny. 

w 

Pleasant        .... 

SE 

Rainy 

Brisk  NW 

Pleasant 

Cloudy 

Pleasant  and 
sunny. 

...Do 

...Do 

Very  pleasant  . . 


Carbon 
dioxide. 


p.ct. 
0.029 
.031 
.033 
.030 
.031 
.030 
.029 
.031 
.030 
.034 
.033 


.029 
.028 
.029 


.030 
.032 
.032 
.029 

:032 

.031 
.031 
.028 

.027 
.027 
.028 
.030 
.030 
.033 

.030 
.030 
.029 
.029 
.030 
.029 
.032 
.030 
.030 

.031 
.030 
.028 
.028 

.027 

.029 
.029 
.029 
.029 
.031 
.030 
.030 
.027 
.029 

.030 
.033 
.033 
.031 
.031 
.030 
.028 

.029 

.033 
.030 
.029 


Apparatus  leaked.     All  stopcocks  were  removed  and  greased. 


Comparative  Air-Analyses 


91 


Table  53. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory.    Series  2 — Cont'd. 

[All  samples  were  taken  from  the  west  side  of  the  laboratory.] 


Date. 


1910. 
May  17 


May  18 
May  20 

May  21 
May  23 

May  24 


May  26 
May  28 
May  31 

June  1 

June  2 

June  4 

June  6 

June  7 
June    8 

June  9 
June  10 
June  11 
June  13 

June  14 
Jime  16 

June  17 
June  18 
June  20 

June  21 
June  22 
June  23 

June  24 

June  25 
June  27 
June  28 
June  29 
June  30 


Time. 


ShSOina-m. 


9  49 
11  01 
11  58 

2  14 

2  57 

3  57 
3  09 

3  42 

4  42 

10  30 

11  42 
3  16 

2  14 

3  24 

1  12 

2  14 
1  19 

3  08 


a.m. 
a.m. 
a.m. 
p.m. 
p.m. 
p.m. 
p.m. 
p.m. 
p.m. 
a.m. 
a.m. 
p.m. 
p.m. 
p.m. 
p.m. 
p.m. 
p.m. 
p.m. 


1  49  p.m. 

2  52  p.m. 
9  09  a.m. 

10  00  a.m. 

2  24  p.m. 

3  27  p.m. 

3  17  p.m. 

4  18  p.m. 


3  05  p.m. 

4  10  p.m. 

2  40  p.m. 

3  31  p.m. 

4  34  p.m. 

5  27  p.m. 

2  10  p.m. 

3  16  p.m. 
9  11  a.m. 

10  14  a.m. 

8  35  a.m. 

9  37  a.m. 

2  28  p.m. 

3  37  p.m. 


8  46 

9  48 

8  35 

9  35 
10  37 

9  05 

1  11 

2  22 

3  25 
8  23 

10  25 

11  30 

8  33 

9  22 
9  03 

10  03 
9  10 

10  11 

11  15 
9  16 

10  10 

11  10 
2  02 
2  54 

10  06 

11  05 
8  55 

10  07 

12  31 
1  23 
8  38 

12  43 


a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
p.m. 
p.m. 
p.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
a.m. 
p.m. 
p.m. 
a.m. 
a.m. 
a.m. 
a.m. 
p.m. 
p.m. 
a.m. 
p.m. 


Temper 
atvire. 


22.8 


15.1 
23.0 


13.7 
20.0 


28.6 


18.0 
17.0 

19!  i 

i4*.7 
16A 

14.0 
20.1 

23!6 
12.3 

iiii 

24!2 

27.1 
i9!7 

i7!8 


26.9 
30.9 

sb'.i 

2612 

24!8 

26!5 
25.0 
24!9* 
24!3 
28!6 


Barom- 
eter. 


mm. 
770.60 


758.55 
762.80 


761.30 
763.00 


756.70 


762.40 

747!46 
748.20 
751.86 
764.65 
757^95 


761.70 

765!  id 
765.25 
766!45 
76i2'.56 

763.15 
765!45 

761.45 
752!9d 


759.50 
758.95 


759.50 
755190 


761.00 

767!35 
759165 
753175 
756175 


758.85 


Wind. 


Light  SW. 


SE 

Light  SE . 


NW. 


W.. 

"sw." 


SW. 


Strong  NE. 
NE.".'.'.'.'. 
SW.".'.'.'.'. 


No  wind 


No  wind 


NE. 


No  wind 


SW. 

SW. 


w 

No  wind 


Light,  E. . 


Light,  SE. 
SW.' ".'.'.'. 


NW. 

NW. 
W.'. 


Weather. 


Pleasant,  warm 
and  sunny. 


Rain 

Pleasant,  sunny 


No  wind 

Light  SE 

Rainy,  misty  . . . 
Cloudy 

No  wind 

Pleasant 

No  wind 

Showery 

SE 

Cloudy  part  of 

time;  sunny. 
Not  sunny 

Strong  NW 

SW 

Cloudy 

SE 

Very  pleasant   . . 

Rainy  day,  but 
not  raining 
when  analyses 
were  made. 

Rainy 


Pleasant,  sunny 


Pleasant,  suimy 
Rainy 


Rainy 


Changeable. 

cloudy    and 

sxmny. 
Pleasant,  simny 


Cloudy 


Foggy , 

Cloudy,  showers 


Sunny,  pleasant 
...Do 


Pleasant:    not 

sunny. 
Cloudy 


Simny,  pleasant 
Pleasant 


Pleasant,    but 

not  sunny. 
Cloudy 


Pleasant    and 

sunny. 
Sunny  


Carbon 
dioxide. 


p.ct. 
0.034 

.033 
.034 
.031 
.029 
.028 
.029 
.031 
.032 
.033 
.032 
.030 
.030 
.031 
.031 
.031 
.032 
.034 
.032 

.029 
.031 
.032 
.030 
.030 
.028 
.033 
.031 


.031 
.030 
.028 
.028 
.028 
.028 
.029 
.030 
.028 
.031 
.031 
.030 
.030 
.031 

.030 
.028 
.033 
.032 
.032 
.034 
.030 
.032 
.033 
.030 
.029 
.028 
.030 
.028 
.030 
.029 
.030 
.028 
.030 
.029 
.030 
.031 
.031 
.033 
.030 
.030 
.033 
.031 
.032 
.031 
.031 
.031 


Oxygen. 


p.ct. 
20.922 

20.925 
20.923 
20.921 
20.923 
20.911 
20.911 
20.921 
20.912 
20.913 
20.923 
20.902 
20.920 
20.715 
20.743 
20.911 
20.910 
20.941 
20.942 

20.940 
20.940 
20.920 
20.922 
20.930 
20.931 
20.930 
20.931 


20.930 
20.933 
20.931 
20.921 
20.932 
20.930 
20.931 
20.933 
20.931 
20.930 
20.933 
20.931 
20.941 
20.941 

20.921 
20.921 
20.930 
20.921 
20.923 
20.920 
20.921 
20.933 
20.932 
20.951 
20.920 
20.921 
20.921 
20.918 
20.930 
20.931 
20.929 
20.910 
20.931 
20.909 
20.933 
20.930 
20.921 
20.923 
20.939 
20.939 
20.933 
20.931 
20.921 
20.923 
20.923 
20.923 


92 


Composition  of  the  Atmosphere 


Table  53.- 


-Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory.     Series  2 — Cont'd 

[All  samples  were  taken  from  the  west  side  of  the  laboratory.] 


Date. 

Time. 

Temp 
atur 

er-      Barom- 
e.           eter. 

Wind. 

Weather. 

Carbon 
dioxide. 

Oxygen. 

1910. 
July     1 

Oct.   17 
Oct.   18 
Oct.   19 
Oct.   20 

Oct.  21 

Oct.   24 

Oct.  25 
Oct.  26 

Oct.   27 
Oct.  28 

Dec.    2 
Dec.    6 

Dec.    7 

Dec.    8 

Dec.     9 

Dec.  10 

Dec.  12 
Dec.  13 

Dec.  14 

Ih35n>p.m. 

2  34  p.m. 

3  22  p.m. 

3  09  p.m. 

4  08  p.m. 

°C. 

27.8 

is!? 

18.1 

7.7 

9.8 

'b'.c 

ll.S 

14.1 

8.6 

9.1 

9.7 

10.£ 

9.7 
9.^ 

8.f 
9.2 

lO.C 

—7 

—2 

—0.7 
— 4!i 

— 7!c 

*0.( 

— i.e 

0.5 

mm. 
\           757.30 

763.00 
758.70 

765.85 

759.50 

757;56 


75b'.36 
752.15 
748.50 

>  755.50 

» 

>  757.15 
760.00 

757.40 

r          761.75 
}           765!8b 

{           766.95 

)           765!45 
5          770.00 

J           760.50 

Light,  SE 

Cloudy 

p.ct. 
0.029 
.031 
.030 
.030 
.030 
.029 
.032 
.041 
.029 
.027 
.027 
.032 
.029 
.029 

.030 
.029 
.028 
.031 
.032 
.028 
.030 
.030 
.032 
.031 
.030 
.029 
.030 
.030 
.027 
.027 
.032 
.030 
.032 
.027 
.029 
.031 
.030 
.029 
.030 
.028 
.030 
.028 
.032 
.031 
.032 
.031 
.029 
.031 
.030 
.033 
.030 
.028 
.028 
.027 

.027 
.030 
.028 
.028 
.031 
.031 
.031 
.028 
.029 
.029 
.028 
.029 
.029 
.030 
.030 
.030 
.032 
.030 
.030 
.030 
.030 
.032 
.031 

20.923 
20.933 
20.934 
20.930 
20.951 

2b;921 
20.942 
20.941 
20.960 
20.900 
20.932 
20.930 

20.928 
20.930 

2b!932 
20.931 

2b;953 
20.941 
20.941 
20.923 
20.924 
20.920 
20.941 
20.939 
20.950 
20.949 
20.953 
20.943 

2b!940 
20.942 

2b;932 
20.932 

2b!941 
20.951 
20.940 
20.943 

20.921 
20.940 
20.939 

20.941 
20.943 
20.932 

20.942 
20.943 
20.922 
20.940 
20.890 
20.943 
20.942 
20.900 
20.941 
20.942 
20.862 
20.941 
20.943 

8  53  a.m. 

9  40  a.m. 
11  25  a.m. 

2  36  p.m. 
11  53  a.m. 

3  05  p.m. 

4  16  p.m. 

9  00  a.m. 

9  45  a.m. 
2  37  p.m. 

9  18  a.m. 

10  25  a.m. 

11  33  a.m. 

2  34  p.m. 

3  36  p.m. 

8  49  a.m. 

9  45  a.m. 
10  44  a.m. 

8  56  a.m. 

10  09  a.m. 

11  37  a.m. 
2  35  p.m. 

2  31  p.m. 

3  23  p.m. 

9  07  a.m. 
9  57  a.m. 

3  08  p.m. 
11  27  a.m. 

10  24  a.m. 

11  30  a.m. 

12  14  p.m. 



SW 

Warm  and  pleas- 
ant. 
Rain. 

Pleasant  

No  wind 

NE 

NW 

Cool  and  pleas- 
ant. 

Light,  SW 

Strong  NW. 

NW 

SW 

SW 

NW 

NW 

Light  8  n  o  w  - 
storm,  first  of 
the  winter. 

Bright,  sunny  .  . 

Light,  NW 

2  10  p.m. 

3  00  p.m. 
9  07  a.m. 

10  03  a.m. 

11  37  a.m. 

12  23  p.m. 

2  15  p.m. 

3  05  p.m. 

4  13  p.m. 
10  13  a.m. 

9  25  a.m. 
10  13  a.m. 

9  41  a.m. 

10  30  a.m. 

11  18  a.m. 

Light,  W 

w 

Bright,  sunny  .  . 

Light,  W 

Pleasant 

Bright,  sunny  . . 
Bright,  sunny  . . 

Light,  NW 

SW 

Comparative  Air-Analyses  93 

Table  53. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory.     Series  2 — Cont'd. 

[All  samples  were  taken  from  the  west  side  of  the  laboratory.] 


Date. 

Time. 

Temper- 
ature. 

Barom- 
eter. 

Wind. 

Weather. 

Carbon 
dioxide. 

Oxygen. 

1910. 
Dec.  15 

Deo.  19 
Dec.  20 

Dec.  22 

Dec.  23 

1911. 

Jan.    18 

Jan.   20 

Jan.   21 
Feb.  10 

9»43™a.m. 

10  42  a.m. 

11  04  a.m. 
11  53  a.m. 

2  20  p.m. 

9  41  a.m. 

10  37  a.m. 

11  32  a.m. 

2  04  p.m. 

10  38  a.m. 

11  38  a.m. 
9  42  a.m. 

3  10  p.m. 

4  14  p.m. 
9  31  a.m. 

10  44  a.m. 

11  52  a.m. 
3  29  p.m. 
9  17  a.m. 

"C. 
2.4 

*6!6 

"4:A 

'i!9 

"o'.d 
oio 

6.4 
0.8 

Tntn> 
748.65 

7I7.66 

77b!26 
77i'.66 

767!25 

Light,  SW 

Not  bright  and 
sunny. 

ab28 

.030 
.030 
.032 
.031 

.032 
.030 
.031 
.032 
.032 
.032 
.032 
.031 

.031 
.033 

.030 
.029 
.029 
.030 
.029 
.027 
.030 
.028 
.028 

20.& 

20,941 
20.921 
20.933 
20.962 

20.831 

26!942 
20.831 
20.932 
20.931 
20.923 
20.952 

20.960 
20.960 

20.950 
20.961 
20.961 
20.951 
20.969 
20.960 
20.961 
20.964 
20.961 

Light,  W 

Rained  in  a.m., 
but  not  raining 
when  analyses 
were  made. 

NW. 

Bright  and  simny 
Pleasant 

'  Light,*  SW. "!!.'! 

Light,  W 

Pleasant     and 
simny. 

766'.35 
754.60 
758.00 

Light,  SE 

Brisk  SW 

Light,  NW 

Pleasant 

Cloudy 

Pleasant 

As  an  examination  of  the  results  showed  frequent  marked  altera- 
tions in  oxygen  content,  numerous  experiments  were  made  with  a  view  to 
changing  experimental  conditions,  an  accurate  Haldane  apparatus  being 
often  used.  The  variations  persisted,  however,  and  while  the  year's  work 
from  November  3,  1909,  to  February  15,  1911,  fully  substantiated  the 
observations  of  earlier  experimenters,  by  no  stretch  of  the  imagination 
could  a  relationship  be  established  between  the  oxygen  percentages  and 
meteorological  conditions,  nor  could  any  adequate  explanation  be  found 
as  to  their  cause  or  causes.  The  significant  fact  that  there  was  no  cor- 
responding alteration  in  the  carbon-dioxide  content — this  factor  remain- 
ing constant  under  all  conditions  of  wind  direction — led  us  to  the  belief 
that  the  oxygen  percentage  also  approximated  constancy,  and  that  the 
discrepancies  appearing  in  the  results  might  be  attributed  to  errors  in 
either  the  technique  or  the  apparatus. 


CONTROL  ANALYSES. 

To  determine  the  source  of  error  it  was  necessary  to  make  duplicate 
analyses  on  another  apparatus  exactly  similar  in  shape;  consequently 
Rudolph  Grave,  of  Stockholm,  was  commissioned  to  construct  a  second 
apparatus.  In  the  fall  of  1910  this  apparatus  reached  Boston,  but  un- 
fortunately had  been  utterly  demolished  in  transit.  Since  it  was  then 
too  late  in  the  season  to  secure  a  third  apparatus  for  the  winter's  work, 
the  lack  of  control  analyses  was  a  very  serious  drawback.  Finally,  a  cylin- 
der of  compressed  air  was  secured  from  the  compressed-air  plant  of  the 
Laboratory  of  Mechanical  Engineering  at  the  Massachusetts  Institute  of 


94 


Composition  of  the  Atmosphere 


Technology  for  the  purpose  of  making  control  analyses  of  the  air  in  the 
cylinder.  The  steel  cylinder  employed,  which  had  formerly  been  used 
for  compressed  oxygen,  was  repeatedly  exhausted  by  a  vacuum-pump  and 
outdoor  air  admitted.  It  was  assumed  that  the  inner  walls  of  the  cylin- 
der would  not  absorb  oxygen  from  the  air  rapidly.  It  was  furthermore 
assumed  that  air  stored  in  the  large  compressed-air  chamber  of  the  In- 
stitute of  Technology  would  be  thoroughly  mixed  and  have  a  fairly  con- 
stant composition.  Employing  precisely  the  same  technical  routine, 
samples  of  the  cylinder  air  were  frequently  analyzed  as  a  control  on  the 
analyses  of  the  outdoor  air.  The  results  of  these  analyses  made  between 
December  3,  1910,  and  February  9,  1911,  are  given  in  table  54. 


Table  54 

— Analyses  made  at  the  Nutrition  Laboratory  of  air  confined  in  a  steel  cylinder. 
Series  1. 

Date. 

Time. 

Carbon 
dioxide. 

Oxygen. 

Date. 

Time. 

Carbon 
dioxide. 

Oxygen. 

1910. 

p.cL 

p.ct. 

1910. 

p.ct. 

p.ct. 

Dec.    3 

9h34-a.m. 

0.033 

20.950 

Dec.  28 

9i'38'"a.m. 

0.032 

20.920 

Dec.    6 

2  35  p.m. 

.033 

20.942 

10  44  a.m. 

.032 

20.911 

3  37  p.m. 

.032 

20.943 

11  43  a.m. 

.033 

20.951 

Dec.    7 

4  48  p.m. 

.034 

20.941 

3  37  p.m. 

.032 

20.949 

Dec.    8 

4  03  p.m. 

.034 

20.943 

1911. 

Dec.    9 

2  56  p.m. 

.032 

20.940 

Jan.  21 

2  32  p.m. 

.031 

20.951 

Dec.  10 

10  14  a.m. 

.031 

20.937 

3  43  p.m. 

.033 

20.950 

Dec.  13 

12  02  p.m. 

.034 

20.938 

Jan.  23 

9  37  a.m. 

.032 

20.951 

Dec.  15 

11  52  a.m. 

.031 

20.922 

10  52  a.m. 

.033 

20.952 

Dec.  22 

2  31  p.m. 

.033 

20.922 

Jan.  31 

10  03  a.m. 

.032 

20.962 

3  43  p.m. 

.033 

20.930 

11  30  a.m. 

.033 

20.975 

4  52  p.m. 

.034 

20.933 

Feb.    9 

.034 

20.913 

Dec.  23 

10  50  a.m. 

11  58  a.m. 
3  24  p.m. 

.034 
.032 
.032 

20.912 
20.920 
20.932 

As  the  simultaneous  analyses  of  outdoor  air  and  cylinder  air  pro- 
gressed, it  soon  became  apparent  that  there  was  some  intimate  relation 
between  the  fluctuations  in  oxygen  content  of  the  outdoor  air  and  the 
fluctuations  observed  in  the  oxygen  content  of  the  cylinder  air.  Further- 
more, while  a  steady  slight  decrease  in  the  oxygen  percentage  of  cylinder 
air  might  have  been  expected,  as  a  matter  of  fact  the  fluctuations  were 
such  as  to  indicate  at  times  apparent  increases.  This  was  conclusive 
evidence  that  in  spite  of  all  precautions  and  delicacy  of  manipulation, 
the  observed  fluctuations  in  the  oxygen  content  of  outdoor  air  might  well 
be  due  to  errors  in  technique. 


THIRD  ROUTINE,   AND  RESULTS  OBTAINED. 

The  fluctuations  in  the  oxygen  content  of  the  cylinder  air  led  to  the 
belief  than  an  error  was  introduced  by  the  distillation  of  water  from  the 
measuring  pipette  over  into  the  strong  alkali.  A  series  of  test  experiments, 
which  occupied  several  weeks,  almost  to  the  exclusion  of  regular  air- 
analyses,  finally  resulted  in  an  alteration  in  the  routine  on  February  15, 


Comparative  Air-Analyses 


95 


1911.  A  further  change  was  made  at  this  time  which  was  due  to  the  fact 
that  at  the  end  of  an  analysis  the  potassium  pyrogallate  was  in  contact 
with  pure  nitrogen  in  the  capillary  tube  inside  the  chamber,  while  the 
reagent  in  the  outer  part  of  the  reagent  chamber  was  in  contact  with  air. 
This  was  remedied  by  the  attachment  of  a  double  bulb  to  the  tube  through 
which  the  chamber  is  filled.  This  double  bulb  provided  a  seal,  one  bulb 
containing  water  and  the  other  air.  When  a  sample  of  air  was  forced 
into  the  pyrogallate  vessel,  the  reagent,  rising  on  the  outside  of  the  inner 
tube,  forced  the  gas  above  it  into  the  first  bulb,  thereby  expelling  the 
water  which  it  contained  into  the  second  bulb. 

The  modified  routine  adopted  on  February  15,  1911,  was  as  follows: 
After  absorbing  the  carbon  dioxide,  the  air  was  sent  back  and  forth  into 
the  potassium  pyrogallate  five  times,  being  left  there  each  time  10  seconds. 
The  first  reading  was  then  taken.  Following  this  the  air  was  again  sent 
into  the  potassium  pyrogallate  for  10  seconds  and  a  second  reading  taken. 
This  procedure  was  carried  on  until  the  readings  were  essentially  constant. 
About  this  time  a  change  was  also  made  in  the  carbon-dioxide  routine. 
As  it  appeared  unnecessary  to  make  two  readings  of  this  factor,  the  first 
reading  was  omitted,  although  the  procedure  for  transfer  of  air  to  and 
from  the  potassium-hydroxide  pipette  was  not  altered  in  any  way.  With 
this  routine,  therefore,  the  air  was  passed  from  the  measuring  pipette  into 
the  potassium  pyrogallate  a  maximum  of  eight  times.  A  sample  analysis 
made  with  the  third  routine  is  given  in  table  55. 

Table  55. — Results  obtained  on  a  sample  of  outdoor  air  with  third 
routine,  February  20,  1911,  4^  25^  p.  m. 


Reading. 

Carbon 
dioxide. 

Oxygen. 

First     

Second  

Third 

p.ci. 
0.028 

p.ci. 

20.930 
20.941 
20.949 
20.952 

Fourth  

Thiit  routine  was  followed  for  but  two  days  in  the  regular  air-analyses; 
the  few  1 -suits  are  given  in  table  56.  During  the  period  from  February 
16  to  March  10  the  cylinder  air  was  likewise  more  or  less  continually 
analyzed,  the  third  routine  being  used.     (See  table  57.) 

Table  56. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory.    Series  3. 


Date. 

Time. 

'Tempera- 
ture. 

Barom- 
eter. 

Wind. 

Weather. 

Carbon 
dioxide. 

Oxygen. 

1911. 
Feb.  20 

1 
Feb.  21 

p.m. 

4  25 
2  15 
2  40 

—5 
—2.8 

mm. 

755.00 
761.75 

NW. 

Snowing  all  day . . 

p.ct. 

0.028 
.031 
.028 
.028 
.030 

20.951 
20.950 
20.952 
20.940 
20.941 

W.. 

Sunny,  pleasant . . 

96 


Composition  of  the  Atmosphere 


Table  57. — Analyses  made  at  the  Nutrition  Laboratory  of  air  confined  in  a  steel  cylinder. 

Series  2. 


Temper- 

Temper- 

1 

Date. 

Time. 

atm-e  of 
water- 

Carbon 
dioxide. 

Oxygen. 

Date. 

Time. 

ature  of  Carbon 
wateiv   dioxide. 

Oxygen. 

bath. 

bath. 

1911. 

°C. 

p.ct. 

p.ct. 

1911. 

"C. 

p.ct. 

p.ct. 

Feb.  16 

8h30'"a.m. 

19.4 

0.034 

20.951 

Feb.  27 

10h30ma.m. 

17.1 

0.033 

20.929 

19.6 

.034 

20.950 

11  00  a.m. 

17.0 

.032 

20.933 

11  15  a.m. 

19.6 

.035 

20.941 

12  00  noon 

26.0 

.032 

20.943 

2  15  p.m. 

19.4 

.036 

20.951 

3  30  p.m. 

24.8 

.030 

20.932 

19.7 

.035 

20.953 

25.2 

,029 

20.939 

Feb.  18 

2  15  p.m. 

20.4 

.033 

20.952 

25.7 

.030 

20.931 

20.6 

.033 

20.949 

Feb.  28 

8  45  a.m. 

16.7 

.033 

20.910 

Feb.  20 

19.6 
20.1 

.035 
.033 

20.938 
20.943 

9  25  a.m. 
9  45  a.m. 

16.8 
16.9 

.034 
.033 

20.930 
20.930 

5  66  p.m. 

Feb.  21 

17.5 

.033 

20.931 

10  15  a.m. 

16.8 

.035 

20.931 

17.3 

.033 

20.932 

11  05  a.m. 

26.0 

.032 

20.922 

17.9 

.034 

20.935 

11  25  a.m. 

26.3 

.028 

20.942 

25.9 

.032 

20.942 

11  50  a.m. 

25.9 

.030 

20.941 

11  45  a.m. 

25.3 

.033 

20.941 

Mar.    1 

2  35  p.m. 

16.8 

.033 

20.921 

25.3 

.032 

20.950 

3  10  p.m. 

16.8 

.034 

20.921 

25.4 

.031 

20.950 

3  35  p.m. 

16.5 

.034 

20.920 

3  45  p.m. 

17.2 

.033 

20.900 

4  00  p.m. 

17.0 

.033 

20.920 

4  20  p.m. 

17.3 

.033 

20.933 

17.2 

.033 

20.921 

5  00  p.m. 

17.3 

.035 

20.931 

Mar.    2 

4  00  p.m. 

16.4 

.033 

20.882 

Feb.  22 

8  25  a.m. 

17.4 

.034 

20.927 

16.5 

.035 

20.911 

9  30  a.m. 

26.1 

.035 

20.920 

16.7 

.031 

20.901 

9  65  a.m. 

26.1 

.032 

20.939 

Mar.    3 

8  30  a.m. 

18.1 

.034 

20.932 

10  50  a.m. 

25.3 

.035 

20.930 

9  00  a.m. 

18.1 

>.033 

20.923 

11  25  a.m. 

25.5 

.034 

20.941 

9  30  a.m. 

18.1 

.033 

20.929 

Feb.  23 

8  30  a.m. 

17.7 

.034 

20.929 

10  00  a.m. 

18.1 

.033 

9  00  a.m. 

16.8 

.035 

20.931 

10  30  a.m. 

18.0 

.034 

20.930 

9  35  a.m. 

17.2 

.033 

20.930 

11  00  a.m. 

17.8 

.034 

20.931 

10  30  a.m. 

26.2 

.032 

20.922 

Mar.    4 

2  20  p.m. 

19.6 

.035 

20.929 

10  55  a.m. 

26.0 

.029 

20.949 

2  45  p.m. 

19.7 

.034 

20.930 

11  30  a.m. 

25.9 

.031 

20.941 

3  15  p.m. 

19.8 

.034 

20.921 

12  00  noon 

25.8 

.030 

20.939 

Mar.    6 

18.5 

.034 

20.920 

Feb.  24 

8  25  a.m. 

16.6 

.033 

20.920 

18.7 

.031 

20.940 

8  50  a.m. 

16.3 

.034 

20.932 

18.6 

.034 

20.919 

9  20  a.m. 

16.1 

.034 

20.921 

Mar.    7 

8  40  a.m. 

18.5 

.032 

20.910 

10  20  a.m. 

26.4 

.033 

20.938 

18.5 

.034 

20.920 

10  50  a.m. 

26.1 

.032 

20.930 

9  25  a.m. 

18.6 

.034 

20.912 

11  15  a.m. 

26.0 

.031 

20.930 

3  15  p.m. 

18.8 

.033 

20.912 

Feb.  25 

2  30  p.m. 

17.2 

.033 

20.921 

18.4 

.033 

20.910 

3  00  p.m. 

17.3 

.033 

20.920 

18.5 

.034 

Feb.  27 

16.4 
16.6 

.032 
.033 

20.930 
20.941 

Mar.  10 

8  40  a.m. 

18.6 
17.9 

.031 
.033 

20.930 
20.921 

9  50  a.m. 

EFFECT  ON   OXYGEN   ABSORPTION   OF  HIGH   AND   LOW  TEMPERATURES. 

An  examination  of  the  results  in  table  57  shows  an  approach  to  con- 
stancy, but  the  variations  are  still  too  wide  to  be  permitted  in  this  study. 
During  this  period  it  is  seen  that  the  temperature  of  the  water-bath  had 
a  wide  variation,  ranging  from  16.1°  C.  to  32.2°  C.  Owing  to  the  fact  that 
a  number  of  investigators  with  whom  I  had  conferred  in  a  recent  European 
tour  had  suggested  that  the  absorption  of  oxygen  might  be  profoundly 
affected  by  changes  in  temperature,  the  wide  range  was  artificially  pro- 
duced for  the  special  purpose  of  studying  this  particular  point.  From 
the  data  in  table  57  the  volumes  for  the  various  temperatures  have  been 
rearranged  so  as  to  give  the  average  results  at  approximately  an  average 
temperature.  These  results  have  been  incorporated  in  table  58.  An  ap- 
parently constantly  decreasing  percentage  of  carbon  dioxide  is  not  con- 
sidered here,  since  subsequent  experiments  show  that  the  decrease  is  not 
an  inevitable  accompaniment  of  increased  temperature.  The  oxygen  de- 
terminations show  a  difference  of  0.01  per  cent  between  the  value  at 
17.1°  C.  and  that  at  25.8°  C,  but  an  insignificant  difference  between  the 


y 


Comparative  Air-Analyses 


97 


value  at  25.8°  C.  and  that  6  degrees  higher.  The  low  value  at  17.1°  C. 
may  in  part  be  attributed  to  the  well-known  slow  absorbing  action  of 
potassium  pyrogallate  at  low  temperatures.  From  these  results  we  may 
safely  conclude  that  temperature  changes  in  the  reagent  are  without 
appreciable  effect  upon  the  absorption  of  oxygen  within  the  limits  men- 
tioned, i.e.,  between  17.1°  C.  and  31.8°  C. 

Table  68. — Analyses  made  at  the  Nutrition  Laboratory  of  air  confined  in  a  steel  cylindeTf 
iLsing  high  and  low  temperatures  of  water-bath. 


Tempera- 
ture of 
water-bath. 

Carbon 
dioAide. 

Oxygen. 

Temper- 
ature of 
water- 
bath. 

Carbon 
dioxide. 

Oxygen. 

Temper- 
ature of 
water- 
bath. 

Carbon 
dioxide. 

Oxygen. 

17.8 

17.3 
17.9 
17.2 
17.3 
17.2 
17.4 
17.7 
16.8 
17.2 
16.6 
16.3 
16.1 

Avg.  17.1 

p.ct. 
0.033 

.033 
.034 
.033 
.033 
.035 
.034 
.034 
.035 
.033 
.033 
.034 
.034 

.033 

20.931 
20.932 
20.935 
20.900 
20.933 
20.931 
20.927 
20.929 
20.931 
20.930 
20.920 
20.932 
20.921 

"C. 
25.9 
25.3 
25.3 
25.4 
26.1 
26.1 
25.3 
25.5 
26.1 
26.0 
25.9 
25.8 
26.4 
26.1 
26.0 

25.8 

p.ct. 
0.032 
.033 
.032 
.031 
.035 
.032 
.035 
.034 
.032 
.029 
.031 
.030 
.033 
.032 
.031 

.032 

20.942 
20.941 
20.950 
20.950 
20.920 
20.939 
20.930 
20.941 
20.922 
20.949 
20.941 
20.939 
20.938 
20.930 
20.930 

"C. 
32.2 
31.3 
31.4 
31.8 
31.9 
31.9 
31.9 
31.7 

31.8 

p.ct. 

0.032 
.030 
.029 
.030 
.031 
.028 
.030 
.031 

.030 

p.ct. 
20.940 
20.932 
20.933 
20.943 
20.941 
20.949 
20.949 
20.941 

20.927 

20.937 

20.941 

Errors  in  the  third  routine. — Two  fundamental  alterations  in  routine 
were  introduced  at  this  time.  Miss  Johnson  called  my  attention  to  the 
fact  that  after  absorbing  the  oxygen,  to  connect  the  pipette  B  with  the 
manometer  and  then  subsequently  to  send  the  air  into  the  potassium 
pyrogallate  was  illogical  for  the  following  reason: 

When  the  stop-cock  a  is  turned  so  as  to  communicate  the  gas  in  B 
with  the  manometer,  there  is  in  B  only  nitrogen.  On  the  other  hand,  in 
the  capillary  between  the  stop-cocks  a  and  d  there  is  air.  During  the 
short  time  required  to  set  the  manometer  and  take  the  reading,  there  is 
unquestionably  a  slight  diffusion  of  air  from  the  capillary  into  the  chamber 
B.  Subsequently,  when  this  gas  is  passed  into  the  potassium  pyrogallate, 
there  is  a  further  contraction  in  volume  which  results  in  a  considerable 
increase  in  the  apparent  percentage  of  oxygen.  Probably  the  increased 
percentages  found  when  the  gas  was  repeatedly  passed  into  the  reagents 
were  due  to  this  fact  rather  than  to  the  distillation  of  water.  It  was  ap- 
parent, therefore,  that  before  connection  with  the  manometer  is  made,  the 
gas  must  be  sufficiently  in  contact  with  the  potassium  pyrogallate  to  ab- 
sorb all  of  the  oxygen,  and  that  no  subsequent  passage  of  the  gas  in  A 
into  the  reagent  should  be  made.  Accordingly  the  routine  was  so  changed 
as  to  secure  these  conditions. 


98  Composition  of  the  Atmosphere 

Shortly  prior  to  this,  it  was  believed  that  when  the  mercury  was  raised 
and  lowered  in  pipette  B,  the  amount  of  water  adhering  to  the  walls  of 
the  lower  bulb  and  graduated  portion  would  vary,  and  that  these  differ- 
ences might  play  a  very  important  role  in  determining  the  percentage  of 
oxygen.  Experiments  were  accordingly  made  to  find  the  oxygen  per- 
centage in  air  more  or  less  dry,  but  these  were  unsuccessful.  Finally,  it 
was  decided  that  if  an  excess  of  water  was  present  in  the  pipette  the  same 
relative  amount  of  water  would  probably  adhere  to  the  glass  walls  each 
time. 

A  large  number  of  experiments  were  made  to  determine  the  amount 
of  water  which  should  be  added  to  obtain  a  clear  meniscus  for  reading  and 
to  insure  constancy  in  the  amount  of  water  in  the  pipette.  At  first  minute 
quantities  of  water  were  used,  the  attempt  being  made  to  secure  only 
enough  to  saturate  the  gas  with  moisture.  It  was  assumed  that  when  the 
mercury  was  lowered  the  liquid  water  would  adhere  to  the  inside  of  the 
upper  bulb,  so  that  only  the  mercury  would  enter  the  constricted  portion 
of  the  pipette  and  the  lower  bulb,  and  that  no  liquid  water  would  be  pres- 
ent. Under  these  conditions,  however,  it  was  found  very  diflicult  to  set 
the  meniscus,  and  the  following  routine  was  finally  decided  on: 

FOURTH  ROUTINE,  AND  RESULTS  OBTAINED. 

Outline  of  fourth  routine. — The  nitrogen  resulting  from  the  previous 
analysis  was  stored  temporarily  in  the  potassium-pyrogallate  pipette,  the 
capillary  tube  leading  to  the  carbon-dioxide  absorption  chamber  C  also 
being  filled  with  nitrogen.  The  stop-cock  a  was  next  removed  and  the 
mercury  in  the  pipette  B  raised  up  through  the  capillary  to  the  stop-cock. 
Water  was  then  added  and  the  mercury  simultaneously  lowered  until 
there  was  a  layer  of  17  mm.  of  water  above  it  in  the  capillary  tube. 
The  stop-cock  a  was  again  put  in  place,  the  nitrogen  withdrawn  from 
the  pyrogallate  reservoir,  and  the  sample  taken  and  analyzed  as  usual. 

Results  with  fourth  routine, — The  analyses  made  with  this  routine  were 
continued  from  March  28  to  April  10,  1911.  The  results  are  given  in 
table  59.  When  these  results  are  compared  with  those  of  earlier  experi- 
ments, it  will  be  noted  that  notwithstanding  the  differences  in  tempera- 
ture, barometer,  direction  of  the  wind,  and  other  conditions,  the  oxygen 
determinations  show  a  striking  uniformity,  the  variations  previously 
found  practically  disappearing. 

This  new  routine  was  also  used  for  the  analyses  of  cylinder  air,  which 
provided  an  excellent  control  of  the  apparatus  and  method.  The  results 
for  the  period  between  March  28  and  April  14, 1911,  are  given  in  table  60. 
Here  again  it  is  seen  that  variations  in  the  oxygen  percentage  are  rare, 
and  as  used  the  method  may  be  assumed  to  give  constant  results. 


Comparative  Air-Analyses 


99 


Table  59. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory. 

Series  4. 


Date. 


Time. 


Temper- 
ature. 


Barom- 
eter. 


Wind. 


Weather. 


Carbon 
dioxide. 


Oxygen. 


Mar.  28 
Mar.  29 

Mar.  30 
Mar.  31 
Apr.     1 

Apr.     3 

Apr.     4 

Apr.     5 

Apr.  6 
Apr     7 

Apr.  8 
Apr.  10 


llhSOma.m. 
12  00  no<jn 

2  25  p.m. 

3  27  p.m. 

10  01  a.m. 

10  31  a.m. 

10  59  a.m. 

11  28  a.m. 
11  56  a.m. 

2  45  p.m. 

10  21  a.m. 

10  52  a.m. 

8  28  a.m. 

8  58  a.m. 

9  00  a.m. 
9  28  a.m. 
9  57  a.m. 

10  27  a.m. 

11  05  a.m. 

11  37  a.m. 

12  10  p.m. 
8  26  a.m. 
8  54  a.m. 
2  24  p.m. 

2  53  p.m. 
10  06  a.m. 

10  35  a.m. 

11  06  a.m. 

8  43  a.m. 

9  13  a.m. 
9  06  a.m. 
9  32  a.m. 

10  01  a.m. 

11  21  a.m. 

11  49  a.m. 

12  19  p.m. 

8  45  a.m. 

9  15  a.m. 
9  45  a.m. 

3  32  p.m. 


"C. 


7.6 


7.4 
9.6 
5.7 
4.5 

'2.6 

4.2 
'2.1 


14.0 
16.8 

8.6 


mm. 
748.40 


753.85 

751.90 
739.40 
746.i0 
757.45 

770.85 

777.70 
775.40 
759.50 

757.00 
754.40 

769.6o 

772.70 
772.40 


Pleasant 


Light,  SW 


Sunny,  pleasant  . 


N 

Brisk  NW. 


Sunny  at  times,  then 
dark  again. 


Brisk  W  . 

w'.'.'.'.'.'.'. 


Sunny,  pleasant 

Sunny  at  times,  then 

dark. 
Sunny,  pleasant  . . . 


W. 


Sunny,  pleasant  . 


Light,  E. 


Light,  SE 
Light,*  SW.' 


Sunny,  pleasant 

Damp,  raw;  no  sun 


Light,  W. 


Snow  and  sleet  last 

night. 
Snow^  on  ground; 

raining. 
Pleasant,  sunny   .  .  . 


SW 


Sunny,  bright. 


SW.,   mod- 
erate. 


Bright,  sunny 


Light,  W. 
Light,' W! 


Sunny,  pleasant 
Sunny,  pleasant 


p.  ct. 

0.034 
.031 
.033 
.080 

.032 
.030 
.030 
.030 
.029 
.031 
.030 
.029 
.027 
.030 
.029 
.029 
.030 
.028 
.031 
.027 
.029 
.031 
,031 
.031 
.031 
.031 
.032 
.032 
.032 

.033 
.031 
.032 
.029 
.030 
.028 

.028 
.030 
.031 
.030 
.031 
.029 


p.  ct. 
20.938 
20.940 
20.949 
20.942 

20.921 
20.928 
20.938 
20.932 
20.935 
20.939 
20.939 
20.941 
20.938 
20.938 
20.938 
20.938 
20.932 
20.939 
20.925 
20.931 
20.938 
20.940 
20.930 
20,932 
20.931 
20.933 
20.923 
20.929 
20.928 

20.940 
20.939 
20.937 
20.930 
20.931 
20.930 

20.938 
20.938 
20.928 
20.935 
20.932 
20.930 


Table  60. 


-Analyses  made  at  the  Nutrition  Laboratory  of  air  confined  in  a  steel  cylinder. 
Series  3. 


Date. 

Time. 

Carbon 
dioxide. 

Oxygen. 

Date. 

Time. 

Carbon 
dioxide. 

Oxygen. 

1911. 

p.ct. 

V.ct. 

1911. 

V.ct. 

p.  ct. 

Mar. 

28 

ghoe^a.m. 

0.038 

20.930 

Apr.     11 

4h04'np.m. 

0.034 

20.919 

9  25  a.m. 

.034 

20.922 

4  36  p.m. 

.033 

20.912 

10  00  a.m. 

.033 

20.921 

Apr.     12 

8  20  a.m. 

.035 

20.917 

10  30  a.m. 

.032 

20.921 

9  06  a.m. 

.033 

20.913 

4  22  p.m. 

.036 

20.922 

9  40  a.m. 

.033 

20.918 

Mar. 

29 

8  30  a.m. 

.034 

20.919 

10  48  a.m. 

.036 

20.913 

9  20  a.m. 

.036 

20.920 

11  25  a.m. 

.032 

20.915 

12  10  p.m. 

.034 

20.919 

11  57  a.m. 

.033 

20.915 

3  48  p.m. 

.032 

20.918 

2  38  p.m. 

.034 

20.920 

Mar. 

30 

8  35  a.m. 

.031 

20.910 

3  13  p.m. 

.034 

20.912 

9  17  a.m. 

.033 

20.918 

3  53   p.m. 

.031 

20.918 

9  47  a.m. 

.032 

20.919 

Apr.     13 

8  34  a.m. 

.036 

20.910 

11  10  p.m. 

.034 

20.920 

9  05  a.m. 

.036 

20.909 

Apr. 

5 

11  43  a.m. 

.033 

20.920 

9  36  a.m. 

.034 

20.912 

Apr. 

6 

9  57  a.m. 

.033 

20.919 

10  13  a.m. 

.036 

20.911 

Apr. 

7 

10  29  a.m. 

.031 

20.917 

11  06  a.m. 

.034 

20.914 

10  57  a.m. 

.033 

20.911 

11  52  a.m. 

.035 

20.920 

Apr. 

10 

2  54   p.m. 

.035 

20.912 

Apr.     14 

8  56  a.m. 

.034 

20.903 

Apr. 

11 

9  12  a.m. 

.033 

20.910 

9  27  a.m. 

.033 

20.904 

9  46  a.m. 

.033 

20.912 

10  02  a.m. 

.035 

20.913 

3  00  p.m. 

.035 

20.916 

10  35  a.m. 

.033 

20.910 

3  32  p.m. 

.034 

20.910 

11  16  a.m. 

.034 

20.912 

100  Composition  of  the  Atmosphere 

FIFTH  ROUTINE,   AND  RESULTS  OBTAINED. 

A  final  change  in  the  routine  was  made  on  April  15, 1911 .  When  using 
a  layer  of  17  mm.  of  water  in  the  capillary  tube  of  pipette  B  it  was  found 
that  variations  in  the  percentage  of  oxygen  in  cylinder  air  were  occasion- 
ally experienced  which  were  somewhat  greater  than  it  was  believed  the 
method  should  allow.  A  few  preliminary  tests  indicated  that  more  uni- 
form conditions  of  moisture  in  the  pipette  could  be  obtained  by  another 
procedure,  and  the  following  routine  has  since  been  adopted : 

Outline  of  fifth  routine. — The  nitrogen  remaining  from  the  earlier 
analysis  having  been  stored  over  the  potassium  hydroxide  and  potassium 
pyrogallate,  the  stop-cock  h  is  closed  and  the  plug  of  stop-cock  a  is  with- 
drawn. The  pipette  B  is  first  completely  filled  with  mercury.  Water 
is  then  introduced  through  the  open  stop-cock  a,  exactly  as  in  the  pre- 
ceding routine,  and  the  mercury  in  pipette  B  simultaneously  lowered, 
thus  drawing  the  water  down  through  the  capillary  tube  into  the  pipette. 
This  is  continued  until  the  mercury  is  lowered  to  the  zero-point,  and  sev- 
eral times  the  amount  of  water  previously  used  has  been  introduced. 
The  whole  interior  of  the  pipette  is  thus  thoroughly  drenched  with  water. 
The  mercury  is  again  raised,  expelling  all  of  the  visible  water,  so  that  none 
remains  above  the  mercury,  filter  paper  inserted  in  the  cock  opening  being 
used  to  remove  the  water.  The  stop-cock  is  then  inserted,  and  the  ni- 
trogen is  drawn  from  the  two  absorption  pipettes,  the  levels  of  the  potas- 
sium hydroxide  and  potassium  pyrogallate  are  set,  and  the  analysis  pro- 
ceeds in  the  usual  way,  i.e.,  the  carbon  dioxide  is  absorbed  by  sending  the 
gas  twice  into  the  potassium  hydroxide,  taking  but  one  final  reading;  the 
air  is  next  passed  into  the  potassium  pyrogallate  for  5  minutes,  then  with- 
drawn, and  passed  into  the  potassium  hydroxide  once.  It  is  again  drawn 
back  and  passed  into  the  potassium  pyrogallate  for  1  minute,  then  into 
the  potassium  pyrogallate  for  5  minutes,  and  into  the  potassium  hydrox- 
ide once.  The  level  of  the  latter  reagent  is  now  set.  The  gas  is  finally 
sent  into  the  potassium  pyrogallate  for  1  minute,  the  level  is  set,  and  the 
reading  taken.  All  the  capillaries  now  being  filled  with  nitrogen  as  at  the 
beginning  of  the  analysis,  the  contraction  in  volume  represents  the  per- 
centage of  carbon  dioxide  in  the  air  and  the  percentage  of  oxygen  in 
carbon-dioxide-free  air.  This  routine,  which  has  been  followed  without 
any  variation  since  April  15,  1911,  has  proved  eminently  satisfactory. 

Results  with  fifth  routine. — The  results  of  the  analyses  of  uncontami- 
nated  outdoor  air  between  April  15,  1911,  and  January  9,  1912,  as  given 
in  table  61,  are  conclusive  in  showing  that  no  fluctuation  of  any  magnitude 
occurs  in  the  percentage  of  oxygen  in  air.  Certain  values  lower  than  the 
average  may  be  almost  invariably  attributed  to  the  fact  that  after  new 
potassium  pyrogallate  is  placed  in  the  reagent  vessel  the  first  analysis 
is  inclined  to  show  a  somewhat  low  percentage  of  oxygen.  When  it  is 
considered  that  all  of  the  determinations,  with  the  single  exception  of  a 
short  series  from  September  15  to  25,  1911,  are  reported,  the  accidental 
variations  are  indeed  inconsiderable. 


Comparative  Air-Analyses 


101 


Table  61. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory .    Series  5. 


Date. 

Time. 

Temper- 
ature. 

Barom- 
eter. 

Wind. 

Weather. 

Carbon 
dioxide. 

Oxygen. 

1911. 
Apr.  15 

Apr.  17 

Apr.  22 
Apr.  24 
Apr.  25 
Apr.  26 

Apr.  27 
Apr.  28 

Apr.  28 

Apr.  29 

May    1 
May    2 

May    3 
May    5 

May    6 
May  19 

May  20 
May  22 

May  23 

May  24 
May  25 

May  26 
June     1 

4h25'np.m. 
4  56  p.m. 

11  45  a.m. 
3  00  p.m. 

3  28  p.m. 

4  12  p.m. 
4  48  p.m. 

11  47  a.m. 

12  21   p.m. 
11  15  a.m. 
11  55  a.m. 

8  55  a.m. 

9  33  a.m. 
10  13  a.m. 

8  45  a.m. 

9  25  a.m. 

8  58  a.m. 

9  34  a.m. 

10  05  a.m. 
3  09  p.m. 

3  54  p.m. 

4  31  p.m, 

8  31  a.m. 

9  12  a.m. 

9  57  a.m. 
2  25  p.m. 

2  58  p.m. 

3  43  p.m. 

8  45  a.m. 

9  22  a.m. 

2  53  p.m. 

3  36  p.m. 

8  26  a.m. 

9  14  a.m. 

9  53  a.m. 

11  26  a.m. 

12  10  p.m. 

2  32  p.m. 

3  03  p.m. 

10  37  a.m. 

11  13  a.m. 
11  54  a.m. 

8  54  a.m. 

9  43  a.m. 

10  29  a.m. 

2  33  p.m. 

3  04  p.m. 

8  45  a.m. 

9  24  a.m. 

10  09  a.m. 
10  48  a.m. 

9  23  a.m. 

10  09  a.m. 

10  47  a.m. 

11  49  a.m. 

12  27  p.m. 

1  04  p.m. 
3  44  p.m. 

8  34  a.m. 

9  33  a.m. 

10  14  a.m. 
9  15  a.m. 
9  57  a.m. 

11  20  a.m. 

11  55  a.m. 

8  40  a.m. 

9  18  a.m. 
9  59  a.m. 
3  52  p.m. 
8  28  a.m. 

10  02  a.m. 

10  09  a.m. 
10  48  a.m. 

12  47  p.m. 
8  55  a.m. 

10  18  a.m. 

2  41  p.m. 

3  19  p.m. 

"C. 

11.8 

10.4 
10.0 

'  3.6 

12.2 

12.4 

Vs.i 

22.9 
24.5 

24.5 

'25.6 

*25.6 

16.7 

22.0 
19.7 

13.5 
'  9.i 

18.6 
26.4 

20.i 

21.4 

*14.i 
19.3 

33.2 

13.9 

12.2 
12.9 

19.2 

17.5 
■21.6 

mm. 
757.15 

758.50 
757.30 

766.05 

765.i5 

766.80 

772.80 

774.70 
776.40 

766.25 

763.90 

76l'.i5 

756.55 

752.85 
750.90 

752.35 
760.60 

768.70 

767.  io 

776.io 

762.40 

762.65 

763.60 
766.10 

763.25 

769.40 

769.45 
766.40 

766.50 

764'.60 
753.20 

Light,  SW. 

Cloudy,    dark, 
-    a.  m.;     bright, 

sunny  at  4  p.m 
Sunny,  pleasant .... 
Do 

p.ct. 
0.031 
•    .031 

.030 
.030. 
.030 
.031 
.029 
.032 
.033 
.032 
.031 
.030 
.031 
.031 
.031 
.030 
.031 
.030 
.031 
.030 
.031 
.031 
.030 
.033 
.032 
.029 
.032 
.032 

1    .030 
?  .031 

.028 
.030 
.031 
.028 
.029 
.028 
.031 
.030 
.029 
.029 
.030 
.028 
.030 
.030 
.031 
.031 
.031 
.031 
.031 
.029 
.029 
.031 
.032 
.032 
.032 
.031 
.032 
.032 
.033 
.033 
.033 
.031 
.030 
.031 
.032 
.029 
.028 
.031 
.029 
.028 
.030 
.029 
.030 
.029 
.029 
.030 
.028 
.028 

p.ct. 
20.941 
20.939 

20.938 
20.940 
20.940 
20.937 
20.931 
20.938 
20.940 
20.943 
20.942 
20.932 
20.940 
20.942 
20.941 
20.939 
20.930 
20.939 
20.937 
20.930 
20.939 
20.938 
20.929 
20.938 
20.932 
20.931 
20.937 
20.939 

20.938 
20.941 

20.939 
20.941 
20.943 
20.931 
20.933 
20.939 
20.942 
20.939 
20.938 
20.921 
20.929 
20.932 
20.933 
20.940 
20.937 
20.937 
20.938 
20.928 
20.932 
20.943 
20.930 
20.930 
20.938 
20.931 
20.938 
20.940 
20.940 
20.942 
20.929 
20.929 
20.931 
20.929 
20.940 
20.940 
20.943 
20.944 
20.942 
20.942 
20.947 
20.940 
20.938 
20.941 
20.938 
20.940 
20.941 
20.939 
20.948 
20.942 

Light,  SW. 
Light,  SW. 

Brisk  NE... 

Cold  raw      .... 

Light,  SE    . 

Sunny,  pleasant 

Light,  SE.  . 

Sunny,  pleasant 

Light,  S.    . . 

Sunny,  pleasant .... 

N 

Sunny,  pleasant 

N 

Sunny,  pleasant 

N 

Sunny,  pleasant .... 

N 

Sunny,  pleasant 

Light.  S.    .. 

Simny,  pleasant .... 

Light,  SW. 

r  Rain  night  before, 
)    clear   but    not 
J    sunny   a  t    time 
i.  of  sampling. 
Bright,  sunny 

Light,  S.    . . 

Brisk  W  . . . 

Sunny    at   times, 
then  dark. 

Brisk  W  . . . 

Sunny,  bright 

Brisk  W.    .. 

Cloudy,  cold 

Light,  SW. 

Sunny,  bright 

N 

Sunny,  pleasant.  .  .  . 

Light,  SW  . 

Sunny,  bright 

SE 

Cloudy 

SE 

E 

Cloudy,  cold,  raw  . . 
Sunny,  smoky 

Brisk  SE.  . . 

Light,  SE.  . 

Sunny,  bright 

Strong  NE 

Cold,    raw,    not 
sunny. 

Brisk  NE  . . 
Light  E.  . . . 

Cold,  not  sunny    . .  . 
Dark;  fog  or  smoke  . 

Brisk  SE.  . . 

Light  SW. . 

Cloudy,  no  rain  . . . . 

Brisk  W     .. 

Sunny,  pleasant .  . .  . 

102 


Composition  of  the  Atmosphere 


Table  61. — Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory. 

Series  5— Cont'd. 

Date. 

Time. 

Temper- 
ature. 

Barom- 
eter. 

Wind. 

Weather. 

Carbon 
dioxide. 

Oxygen. 

1911. 
June    2 

June    3 
June    5 

June    6 

June    7 
June    8 
June    9 
June  10 

June  12 
June  13 

Sept.  26i 
Sept.  27 

Sept.  28 
Sept.  29 

Sept.  30 
Oct.     2 
Oct.     3 
Oct.     4 

Oct.     5 

Oct.     6 
Oct.     7 
Oct.   11 
Oct.   12 

3h59"'p.m. 

8  34  a.m. 

9  14  a.m. 
9  59  a.m. 

8  59  a.m. 

9  42  a.m. 
11  55  a.m. 

2  52  p.m. 

3  33  p.m. 

10  31  a.m. 

11  13  a.m. 

12  19  p.m. 
3  08  p.m. 
3  47  p.m. 

12  32  p.m. 
2  18  p.m. 

2  58  p.m. 

8  30  a.m. 

9  15  a.m. 
9  55  a.m. 

11  50  a.m. 

3  17  p.m. 
3  57  p.m. 

10  45  a.m. 

11  55  a.m. 

2  34  p.m. 

3  11  p.m. 

3  51  p.m. 

4  27  p.m. 
9  10  a.m. 
9  48  a.m. 

10  35  a.m. 

2  40  p.m. 

3  19  p.m. 

8  34  a.m. 

9  18  a.m. 
10  27  a.m. 

12  16  p.m. 

2  43  p.m. 

3  30  p.m. 

4  31  p.m. 

8  56  a.m. 

9  34  a.m. 

8  35  a.m. 

9  09  a.m. 
9  45  a.m. 
4  12  p.m. 
9  07  a.m. 
9  44  a.m. 

10  19  a.m. 

8  46  a.m. 

9  27  a.m. 

10  33  a.m. 

11  53  a.m. 

8  51  a.m. 

9  30  a.m. 
9  13  a.m. 
9  50  a.m. 

8  48  a.m. 

9  27  a.m. 
8  45  a.m. 

10  12  a.m. 

10  51  a.m. 

3  26  p.m. 

12  03  p.m. 
12  37  p.m. 

8  34  a.m. 
2  30  p.m. 

9  10  a.m. 
10  00  a.m. 

"C. 
24*.7 

23.4 
15.4 

12.5 

16.4 
20.5 
25.3 
23.7 

12.7 

15.7 
17.0 

12.4 

lV.8 
*  '8.9 
11.3 
13.6 

18.4 

13.6 
8.0 

20.4 

mm. 
759.40 

765.55 
767.6o 

766.20 

768.45 
767.65 
760.50 
757.30 

755.35 

764.00 
766.55 

764'.55 

762.90 
758.30 
770.30 
760.00 

752.'00 

758.75 

762.65 
762.00 

753.60 

0.029 
.029 
.028 
.030 
.029 
.028 
.028 
.027 
.030 
.028 
.029 
.030 
.030 
.029 
.028 
.029 
.029 
.027 
.029 
.029 
.028 
.029 
.029 
f   .027 
\    .029 
J    .029 
\    .029 
i    .031 
I   .027 
.046 
.032 
.030 
.027 
.029 
.029 
.028 
.033 
.029 
.028 
.031 
.037 

(    .031 
r   .029 

.032 
.032 
.032 
.029 
.030 
.032 
.030 
.033 
.039 
.033 
.031 
.032 
.031 
.030 
.031 
.032 
.031 
.028 
.031 
.031 
.033 
.035 
.030 

.027 
.029 
.028 
.028 
.031 
.027 

p.  ct. 
20.937 
20.943 
20.939 
20.940 
20.937 
20.938 
20.939 
20.939 
20.942 
20.942 
20.941 
20.941 
20.949 
20.943 
20.943 
20.949 
20.942 
20.939 
20.943 
20.942 
20.939 
20.942 
20.943 
20.949 
20.928 
20.934 
20.939 
20.938 
20.941 
20.940 
20.929 
20.939 
20.958 
20.952 
20.939 
20.941 

20.948 
20.930 
20.929 
20.936 

20.935 
20.940 

20.893 
20.930 
20.930 
20.942 
20.949 
20.941 
20.947 
20.932 
20.932 

2d.94i 
20.938 
20.942 
20.942 
20.943 
20.940 
20.939 
20.940 
20.938 
20.928 
20.931 
20.941 

20.934 
20.941 
20.940 
20.941 
20.925 
20.929 

Brisk  W.... 

Sunny,  pleasant 

Light  SW  . . 

Clear;  no  sun 

Brisk  SE... 

Not  sunny 

Brisk  NE  . . 

Rains 

' 

Light  E 

Clear,  bright 

Brisk  NE... 

Sunny,  pleasant 

Light  E.... 

Sunny,  pleasant. . . . 

Light  NE  . . 

1  Warm,  sunny 
I  early;  dark  when 
(  samples  were 
j    taken. 

Light  SE... 

Rained    a.m.;    no 
thimder. 



Light  thunder ; 
heavy  rainfall. 

Light  NW. . 
Light  SW.  . 

r  Not    raining; 
1     rained  early; 
<     heavy  thunder- 
)     storm    night 
L    before. 
Dull,  dark 

Brisk  NW.. 

Sunny,  pleasant. . . . 

Brisk  NW.. 

Sunny,  pleasant. . . . 

Mod.  NW.. 

Rains 

Light  W  . . . 

Sunny,  pleasant 

Brisk  SE  .. 

Dark;  rainy  day  . . . 

*'* 

Briri^SW... 
Brisk  NW. . 

Showers;  not  rain- 
ing now. 

Light  SW  . . 
Mod.  NW. . 

Pleasant 

Rain;  cold;  raw.... 

Light  W  . . . 

Pleasant  

1  Active  expenmentmg  began  again  on  September  15,  1911,  but  the  results  for  the  first  few  days  were 
obviously  influenced  by  some  as  yet  undetermined  factor  and  are  not  here  included.  These  are  the  only 
omissiont  in  the  entire  series. 


Comparative  Air-Analyses 


103 


Table  Ql.— Analyses  of  outdoor  air  made  at  the  Nutrition  Laboratory.    Series  5— Cont'd. 


Date. 


1911. 
Oct.  12 
Oct.  13 
Oct.  17 
Oct.  18 
Oct.  26 


Time. 


Nov.  1 
Nov.  13 


rov.  14 
Nov.  15 


Nov.  17 
Nov.  20 


Dec.  4 

Deo.  9 

Dec.  12 
Dec.  13 
Dec.  14 

Dec.  15 

1912 
Jan.  2 

Jan.  3 

Jan.  4 

Jan.  6 
Jan.  9 


3h32mp.m. 

8  48  a.m. 

9  28  a,m, 
4  32  p.m 
9  55  a.m. 

10  33  a.m. 

11  05  a.m. 
3  14  p.m. 

3  23  p.m. 
9  39  a.m. 

10  14  a.m. 

10  51  a.m. 

9  12  a.m. 

10  04  a.m. 

10  38  a.m. 

8  55  a.m. 

9  44  a.m. 
2  25  p.m. 
2  59  p.m. 

k  ^  3  39  p.m. 

4  23  p.m. 

12  12  p.m. 
2  13  p.m. 

2  46  p.m. 

3  31  p.m. 
9  49  a.m. 

10  28  a.m. 

11  04  a.m. 
11  39  a.m. 

2  21  p.m. 


12  01  a.m. 


3  00  a.m. 


10  12  a.m. 

3  57  p.m. 
12  01  a.m. 

3  00  a.m. 

8  47  a.m. 
12  01  a.m. 

3  00  a.m. 
10  29  a.m. 
12  01  a.m. 

3  00  a.m. 

9  13  a.m. 
9  48  a.m. 
9  04  a.m. 


3  59  p.m. 


2  45  p.m. 


4  40  p.m. 

.... 

10  15  a.m. 

—3.0 

2  00  p.m. 

3  25  p.m. 

4  00  p.m. 

.  . . 

8  30  a.m. 

—9.0 

9  30  a.m. 

10  10  a.m. 

8  45  a.m. 

0.0 

9  20  a.m. 

2  45  p.m. 

—6.0 

Temper- 
ature. 


"C. 

*  9.6 
11.5 
12.5 
14.7 


7.5 
1.4 


5.8 


4.6 
4.9 
4.7 


—3.0 
—2.5 

*  7.8 

16.6 

14.6 

'  6.6 
'  '3.8 

*  3.6 


Barom- 
eter. 


mm. 

76i'.70 
768.10 
762.80 
767.00 


763.15 
764.30 

773.20 

749.i5 


764.70 
761.20 


765.15 

765.30 
773.i5 
773.60 
770.30 

766.65 

758.35 

77l'.70 
767.25 

763.50 

758.75 

764*60 

737.50 
744*45 


Wind. 


Brisk  W  . . 
Strong  NE 
Brisk  SE  . 
SW 


Light  NW., 
Brisk  NW!! 


Light  W 


Light  W  . , 
Brisk  W  . , 
Light  W  . , 


Light  NE 


Light  N 


SW 


Light  SW 
Light  SW 


Light  W  . 
tight  Se! 


Light  N  . . . 


Light  NE 


Brisk  NW. , 
Brisk  w!! 


Strong  W  . . 
Average 


Weather. 


Beautiful  clear  day 
Cloudy,  fine  mist  . 
Rained  all  day  .. .. 
Sunny,  pleasant... 


Cold,  raw , 

Sunny,  pleasant... 


Sunny,  bright 


■^  Bright,  sunny; 
(  Ught  fall  of 
>  snow  evening 
I    before,  followed 

J    by  heavy  rain . 

Pleasant 

Cold,  clear 

Cold,  raw 


Cold,  raw;  no  sun 


Cold,  raw 


Quite  foggy  . . . 
Not  very  foggy. 


Dark;  light    misty 
rain. 

Fair    , 

Fair    , 

Sunny,  pleasant. . . . 

Cloudy 

Cloudy 

Cloudy,  unsettled  . . 

Fair    

Fair    

Cloudy,  unsettled  . , 


Light   snowfall   in 
night;  rains  now. 


Pleasant 


Unsettled;     light 
snow  flurries. 


Sunny;  clear,  cold. . 


Rain  early  a.m. 
Now  colder,  clearing 
Clear  and  cold   .... 


Carbon 
dioxide. 

Oxygen. 

p.  rt. 
0.029 

V-ct. 
20.937 

.030 

20.941 

.030 

20.938 

.031 

20.939 

.030 

20.930 

.031 

20.936 

.030 

20.939 

.032 

20.931 

.031 

20.937 

.029 

20.930 

.028 

20.941 

.028 

20.939 

.021 

20.938 

.029 

20.938 

.029 

20.940 

r  .030 

20.935 

)  .028 

20.939 

I     .026 

20.940 

I  .029 

20.942 

L  .029 

20.939 

.027 

20.941 

.026 

20.941 

.028 

20.940 

.030 

20.934 

.029 

20.939 

.029 

20.940 

.030 

20.940 

.028 

20.939 

.030 

20.939 

.031 

20.941 

.031 

20.939 

.034 

20.931 

.035 

20.931 

.033 

20.932 

.034 

20.935 

.030 

20.938 

.031 

20.940 

.029 

20.939 

.029 

20.941 

.028 

20.939 

.028 

20.938 

.030 

20.939 

.029 

20.940 

.029 

20.937 

.030 

20.940 

.028 

20.930 

.030 

20.937 

.027 

20.938 

.032 

20.905 

.038 

20.932 

.031 

20.919 

.031 

20.930 

.029 

20.938 

.031 

20.938 

f  .031 

20.931 

\    .029 

20.930 

I  .031 

20.931 

.029 

20.938 

.032 

20.933 

.029 

20.933 

.028 

20.939 

.031 

20.940 

.029 

20.940 

.029 

20.941 

.028 

20.933 

.031 

20.938 

A  result  so  strikingly  at  variance  with  all  earlier  researches  must  be 
subjected  to  most  critical  examination  and  control.  It  is  possible,  for 
example,  that  the  apparatus  was  mechanically  so  constructed  that  the 
manometer  is  more  readily  set  at  zero  when  the  mercury  in  the  pipette  B 
is  at  20.94  per  cent — a  condition  difficult  to  conceive,  but  nevertheless  not 
absolutely  impossible. 


104 


Composition  of  the  Atmosphere 


For  the  best  proof  of  the  accuracy  and  sensitiveness  of  the  apparatus 
we  must  again  turn  to  our  analyses  of  cylinder  air.  These  were  made  in 
parallel  with  the  analyses  of  outdoor  air  and  continued  from  April  15  to 
June  7,  1911.     The  results  are  given  in  table  62. 


Table  62. — Analyses  made  at  the  Nutrition  Laboratory  of  air  confined  in  a  steel  cylinder^ 

Series  4. 


Date. 

Time. 

Carbon 
dioxide. 

Oxygen. 

Date. 

Time. 

Carbon 
dioxide. 

Oxygen. 

1911. 

p.Ct. 

p.Ct. 

1911. 

p.Ct. 

p.Ct. 

Apr.  16 

ghOeraa.m. 

0.036 

20.909 

May  26 

Ilh37«°a.m. 

0.031 

20.919 

9  52  a.m. 

.033 

20.919 

12  15  p.m. 

.033 

20.911 

10  24  a.m. 

.033 

20.911 

3  27  p.m. 

.035 

11  09  a.m. 

.034 

20.920 

3  58  p.m. 

.036 

20.915 

11  46  a.m. 

.033 

20.912 

May  27 

8  28  a.m. 

.035 

20.899 

12  15  p.m. 

.035 

20.911 

9  04  a.m. 

.034 

20.908 

2  36  p.m. 

.034 

20.918 

9  40  a.m. 

.035 

20.912 

3  06  p.m. 

.034 

20.920 

2  03  p.m. 

.036 

20.909 

3  51  p.m. 

.034 

20.919 

2  42  p.m. 

.034 

20.911 

Apr.  17 

8  51  a.m. 

.036 

20.905 

3  25  p.m. 

.034 

20.913 

9  31  a.m. 

.034 

20.921 

4  07  p.m. 

.033 

20.910 

10  16  a.m. 

.036 

20.918 

May  29 

8  30  a.m. 

.034 

20.902 

10  57  a.m. 

.035 

20.921 

10  39  a.m. 

.•033 

20.911 

Apr.  19 

9  32  a.m. 

.035 

11  30  a.m. 

.033 

20.909 

2  27  p.m. 

.036 

20.918 

2  02  p.m. 

.032 

20.908 

2  52  p.m. 

.035 

20.919 

2  40  p.m. 

.035 

20.909 

Apr.  22 

2  00  p.m. 

.030 

20.905 

May  31 

9  21  a.m. 

.048 

20.903 

3  03  p.m. 

.032 

20.921 

12  02  p.m. 

.033 

20.914 

3  42  p.m. 

.034 

20.922 

2  31  p.m. 

.033 

20.909 

Apr.  24 

8  55  a.m. 

.035 

20.915 

3  15  p.m. 

.033 

20.913 

9  40  a.m. 

.036 

20.909 

4  29  p.m. 

.037 

20.910 

10  27  a.m. 

.036 

20.922 

June   1 

8  23  a.m. 

.033 

20.906 

11  04  a.m. 

.036 

20.919 

9  18  a.m. 

.034 

20.907 

Apr.  25 

9  08  a.m. 

.037 

20.913 

9  55  a.m. 

.033 

20.912 

9  50  a.m. 

.036 

20.920 

10  39  a.m. 

.035 

20.907 

10  28  a.m. 

.036 

20.921 

11  31  a.m. 

.032 

20.903 

May   2 

10  37  a.m. 

.034 

20.919 

12  16  p.m. 

.036 

20.912 

May  19 

3  01  p.m. 

.033 

20.918 

12  53  p.m. 

.034 

20.912 

May  20 

11  15  a.m. 

.037 

20.932 

June   2 

10  43  a.m. 

.032 

20.908 

2  20  p.m. 

.037 

20.910 

11  35  a.m. 

.033 

20.908 

3  11  p.m. 

.037 

20.909 

2  22  p.m. 

.033 

20.905 

3  52  p.m. 

.038 

20.913 

June   3 

10  23  a.m. 

.035 

20.910 

May  22 

12  37  p.m. 

.037 

20.910 

2  28  p.m. 

.031 

20.912 

3  03  p.m. 

.034 

20.907 

3  14  p.m. 

.031 

20.919 

3  48  p.m. 

.010 

20.910 

3  57  p.m. 

.032 

20.920 

May  23 

10  54  a.m. 

.035 

20.919 

June   5 

8  24  a.m. 

.037 

20.914 

11  40  a.m. 

.034 

20.910 

9  02  a.m. 

.036 

20.920 

12  20  p.m. 

.033 

20.919 

9  43  a.m. 

.034 

20.911 

May  24 

9  22  a.m. 

.034 

20.909 

10  30  a.m. 

.034 

20.918 

10  48  a.m. 

.033 

20.910 

11  10  a.m. 

.033 

20.917 

11  35  a.m. 

.035 

20.910 

4  18  p.m. 

.033 

20.914 

12  11  p.m. 

.033 

20.907 

June   6 

8  30  a.m. 

.032 

20.912 

2  48  p.m. 

.032 

20.909 

9  10  a.m. 

.033 

20.912 

May  25 

8  41  a.m. 

.032 

20.909 

9  64  a.m. 

.031 

20.913 

9  19  a.m. 

.033 

20.908 

June   6 

2  29  p.m. 

.033 

20.913 

11  29  a.m. 

.033 

20.918 

June   7 

8  46  a.m. 

.031 

20.910 

12  13  p.m. 

036 

20.910 

9  47  a.m. 

.032 

20.909 

3  00  p.m. 

.036 

20.913 

10  33  a.m. 

.034 

20.919 

3  46  p.m. 

.035 

20.910 

11  13  a.m. 

.034 

20.918 

4  20  p.m. 

.035 

20.912 

11  53  a.m. 

.033 

20.920 

May  26 

8  14  a.m. 

9  36  a.m. 

.033 
.036 

20.910 
20.912 

3  56  p.m. 

.034 

20.914 

Inasmuch  as  the  analyses  indicated  that  the  air  had  remained  ap- 
proximately constant  throughout  several  months,  it  was  believed  that 
the  conditions  inside  the  cylinder  were  not  such  as  to  cause  any  material 
oxidation.  When  the  air-analyses  were  resumed  in  the  fall,  after  a  sum- 
mer of  unprecedented  heat  in  Boston,  the  oxygen  percentage  was  found 
to  have  materially  decreased.  Excluding  a  few  analyses  made  between 
September  15  and  September  25,  we  have  the  results  given  in  table  63. 


Comparative  Air-Analyses 


105 


Table  63. — Analyses  made  at  the  Nutrition  Laboratory  of  air  cmtfined  in  a  steel  cylinder. 

Series  5, 


Date. 

Time. 

Carbon 
dioxide. 

Oxygen. 

Date. 

Time. 

Carbon 
dioxide.  , 

Oxygen. 

1911. 

p.ct. 

p.ct. 

1911. 

p.et. 

p.ct. 

Sept. 

25 

3hl6"p.m. 

0.032 

20.872 

Nov.    15 

lli>26n>a.m. 

0.031 

20.870 

3  58  p.m. 

.034 

20.879 

11  59  a.m. 

.031 

20.871 

4  39  p.m. 

.034 

20.892 

12  34  p.m. 

.032 

20.871 

Sept. 

26 

11  02  a.m. 

.036 

20.889 

Dec.       2 

9  27  a.m. 

.032 

20.859 

11  44  a.m. 

.035 

20.891 

10  07  a.m. 

.030 

20.863 

Sept. 

27 

9  29  a.m. 

.036 

20.881 

10  50  a.m. 

.031 

20.878 

Sept. 

28 

11  00  a.m. 

.035 

20.885 

11  27  a.m. 

.032 

20.878 

Sept. 

29 

11  15  a.m. 

.034 

20.882 

12  03  p.m. 

.032 

20.876 

Sept. 

30 

10  19  a.m. 

.033 

20.883 

2  35  p.m. 

.026 

20.875 

Oct. 

2 

10  41  a.m. 

.033 

20.883 

3  15  p.m. 

.030 

20.872 

Oct. 

3 

10  10  a.m. 

.038 

20.888 

3  57   p.m. 

.033 

20.873 

10  52  a.m. 

.039 

20.880 

4  53  p.m. 

.031 

20.873 

2  25  p.m. 

.038 

20.870 

Dec.       4 

9  10  a.m. 

.032 

20.880 

3  03  p.m. 

.040 

20.873 

3  41  p.m. 

.032 

20.878 

Oct. 

4 

2  42  p.m. 

.032 

20.881 

4  19  p.m. 

.032 

20.875 

Oct. 

5 

2  22   p.m. 

.034 

20.887 

1912 

Oct. 

6 

2  34   p.m. 
4  03   p.m. 

.032 
.032 

20.881 
20.880 

Jan.        6 

.032 
.032 

20.860 
20.860 

12  10  p.m. 

Oct. 

25 

8  54   a.m. 

.021 

20.873 

Jan.        9 

10  00  a.m. 

.033 

20.872 

10  10  a.m. 

.034 

20.873 

10  40  a.m. 

.033 

20.862 

Oct. 

26 

8  44  a.m. 

9  21  a.m. 

.031 
.035 

20.858 
20.861 

11  15  a.m. 

.030 

20.863 

Of  especial  importance  are  the  percentages  for  December  2  and  4, 1911, 
as  they  establish  the  absence  of  any  effect  upon  the  determination  of  car- 
bon dioxide  and  oxygen  resulting  from  the  temperature  of  the  reagents. 
The  percentages  found  were  constant,  independent  of  an  alteration  of 
over  10°  C.  in  the  temperature  of  the  water-bath,  which  ranged  during 
these  analyses  between  20.4°  C.  and  32.5°  C.  These  experiments  with  im- 
proved technique  substantiate  fully  the  observations  on  p.  97. 

CONCLUSIONS  FROM  RESULTS  WITH  FIFTH  ROUTINE. 

From  the  results  of  analyses  given  in  tables  61  and  62,  it  will  be  seen 
that  the  apparatus  gives  constant  oxygen  percentages  for  outdoor  air; 
for  any  particular  day  or  for  a  period  of  3  or  4  days,  the  apparatus  also 
gives  constant  results  for  the  oxygen  content  of  the  cylinder  air,  although 
these  are  measurably  lower  than  those  for  outdoor  air.  These  facts  dem- 
onstrate that  the  constant  readings  are  not  due  to  any  peculiarity  in  the 
construction  of  the  apparatus.  Furthermore,  since  it  is  obvious  from  an 
examination  of  the  results  that  there  is  a  steady,  though  slight,  decrease 
in  the  oxygen  content  of  the  cylinder  air,  the  evidence  in  favor  of  both 
the  accuracy  and  the  sensitiveness  of  this  apparatus  becomes  conclusive. 

On  the  basis  of  this  series  of  observations,  then,  we  may  state  that  the 
uncontaminated  air  of  Boston  is  of  constant  oxygen  content  irrespective 
of  conditions  of  weather,  humidity,  temperature,  barometer,  wind  direc- 
tion, and  season. 

It  may  further  be  stated  that  the  percentage  of  carbon  dioxide  does 
not  undergo  any  material  alteration  under  these  conditions. 

And,  finally,  from  the  evidence  thus  secured,  we  may  assert  that  in 
uncontaminated  outdoor  air  the  approximate  percentage  of  carbon  di- 
oxide is  0.031  and  oxygen  20.938. 


106 


Composition  of  the  Atmosphere 


ANALYSES  OF  AIR  COLLECTED  ON  THE  ATLANTIC  OCEAN. 

Since  numerous  writers  have  found  noticeable  differences  in  air  col- 
lected over  the  sea  as  compared  with  that  collected  on  the  land,  a  number 
of  samples  for  analysis  were  secured  of  air  taken  over  the  Atlantic  Ocean. 
I  am  indebted  for  these  samples  to  Mr.  Harold  L.  Higgins,  of  the  Nutri- 
tion Laboratory,  who  most  carefully  collected  them,  together  with  supple- 
mentary climatic  data,  on  a  sea  trip  between  Montreal  and  Liverpool  in 
November  1910.  The  glass  sampler  used  was  similar  in  form  to  that 
described  by  Regnault,^  and  consisted  of  a  cylindrical  tube  40  mm.  in 
diameter  and  245  mm.  long,  with  a  capacity  of  approximately  200  c.  c. 
To  each  end  of  the  tube  was  attached  a  short  piece  of  glass  tubing,  which 
was  drawn  out  in  a  capillary,  so  that  when  the  sampler  had  been  filled 
it  could  be  sealed  in  the  flame  of  a  candle  or  an  alcohol  lamp.  The 
samples  were  always  taken  on  the  windward  side  of  the  vessel,  the  sam- 
pling tubes  being  filled  by  aspiration  with  the  mouth  for  a  few  minutes. 
A  water-seal  was  provided  by  drawing  the  air  first  through  the  sampler, 
then  through  a  gas-washing  bottle  containing  water  and  attached  by  a 
short  piece  of  rubber  tubing,  thus  preventing  all  contamination  by  ex- 
pired air.  After  sujfficient  aspiration  the  tubes  were  quickly  taken  to  the 
stateroom  and  sealed,  labeled,  and  packed  in  a  specially  constructed 
carrying  case.  No  precautions  were  taken  to  dry  the  air  before  it  entered 
the  sampling  tubes.  Though  the  samples  were  taken  in  November  1910, 
the  analyses  were  not  made  until  a  year  later,  i.e.,  October  6  and  7,  1911. 
The  results  are  presented  in  table  64.  Aside  from  the  constancy  in  the 
oxygen  percentages,  the  most  striking  feature  of  the  results  in  this  table 
is  the  extraordinarily  low  percentage  of  carbon  dioxide  in  the  samples 
collected  on  November  7  and  10.  In  fact,  all  of  the  carbon-dioxide  values 
are  lower  than  normal.^ 

Table  64. — Analyses  of  ocean  air  collected  between  Montreal  and  Liverpool. 


Date 
of  collec- 
tion. 

Time. 

Lat.  N. 

Long.W. 

Temp, 
of  sea- 
water. 

Wind. 

Weather. 

Carbon 
dioxide. 

Oxygen. 

^1910. 

p.m. 

0             , 

o          / 

op 

p.  ct. 

p.ct. 

Nov.    7 

12h30« 

47  23 

59    4 

44 

SE.;mod.to 
fresh. 

Misty  to  foggy; 
overcast. 

0.003 

20.940 

Nov.    8 

12  15 

45  56 

51  15 

48 

NW.;mod.. 

Overcast;    sea 

f.021 
1.023 

20.930 

almost  calm. 

20.932 

Nov.    9 

12  10 

47  22 

42  58 

48 

NW.;mod.. 

Clear,  sun  ny; 
moderate  sea. 

.027 

20.939 

Nov.  10 

12  15 

49  21 

34  39 

57 

S.  to   SW. 

mod. 
S.  to   SW.; 

Overcast,  misty 

.006 

20.940 

Nov.  11 

12  35 

50  42 

25  33 

55 

....Do 

.021 

20.933 

mod.  only. 

Nov.  12 

12  25 

51  10 

15  56 

55 

SW.;    mod. 
to  fresh  only. 

Average 

....Do 

.024 

.... 

20.940 

20.936 

1  Regnault,  Annales  de  Chimie  et  de  Physique,  1852,  ser.  3,  36,  p.  385. 

2  The  injunction  of  Regnault  (Annales  de  Chimie  et  de  Physique,  1852  ser.  3,  36,  p. 
392)  to  collect  samples  of  dry  air  was  unfortunately  not  followed.  As  the  determination 
of  oxygen  percentages  was  the  first  consideration  in  this  study,  no  especial  thought  was 
given  in  taking  the  samples  to  the  determinations  of  the  carbon  dioxide. 


Comparative  Air-Analyses 


107 


A  second  study  of  ocean  air  was  made  possible  through  the  kindness  of 
Mr.  Thome  M.  Carpenter,  of  the  Nutrition  Laboratory,  who  carefully 
collected  a  large  number  of  samples  on  a  return  voyage  from  Genoa  to 
Boston  in  June  1911.  Profiting  by  a  discussion  of  the  problem  with  Dr. 
Krogh  in  Copenhagen,  Mr.  Carpenter  took  special  precautions  to  collect 
several  samples  of  air  dried  over  phosphorus  pentoxide.  Usually  the 
samples  were  taken  by  aspiration  with  the  mouth,  but  in  collecting  the 
dry  samples  it  was  found  that  the  phosphorus  pentoxide  powder  was  me- 
chanically carried  to  the  mouth,  with  consequent  discomfort;  a  rubber 
bulb  was  accordingly  used.  The  samples  were  collected  between  June 
10  and  25,  1911,  but  it  was  inexpedient  to  analyze  them  before  October 
14  to  26,  1911.     The  results  of  these  analyses  are  given  in  table  65. 


Table  65. 

—Analyses  of  ocean  air  collected  between  Genoa  and  Boston 

Date  of 

Time. 

Lat. 

Long. 

Barom- 

Wind. 

General 

Condition 
of 

Car- 
bon 

i 
Oxy-  1 

collection. 

N. 

eter. 

conditions. 

sample. 

diox- 
ide. 

gen. 

1911. 

o     / 

o      / 

mm. 

V.ct. 

v.u. 

June  10 
June  12 

llhooraa.m. 

746.0 
754.1 

Bay  of  Genoa    .... 
Naples;    cloudless 

Moist . . 
Moist . . 

0.034 

90  Q3« 

5  15  p.m. 

'.'.   '.'. 

Almost 

.011i20.93i! 

headwind; 

sky;    temp,    on 

Moist . . 

.016  20.933 

strong. 

deck20-21»C. 

June  15 

11  45  a.m. 

12  00  noon 

38  47 

9  04E 



1st  day  out  from 
Naples;  moderate 

Moist . . 
Moist . . 

.022  20.933 
.019120.925 

head  sea. 

.019'20.931 1 

June  16 

11  40  a.m. 

12  10  p.m. 
11  50  a.m. 

37  17 

1  27E 

753.8 

Fair 

Temp,   on    deck 
21.5°  C;  steamer 
going  with  wind; 
calm  sea. 

Moist . . 
Moist . . 
Moist . . 

.010  20.9301 
.018(20.935 1 
.012  20.932! 
.017  20.938! 

June  17 

11  40  a.m. 

35  58 

5  SOW 

752.0 

VeryUttle.if 
any;  fresh 
breeze  pre- 
viouseven- 

Clear  early  morn- 
ing; clouded  over 
at    noon;    very 
calm  sea;   temp, 
on  deck,  20.7"  C. 

Moist . . 

.018 

20.929 

ing. 

June  18 

36  40 

13  IIW 

754.0 

Temp,  on  deck  in 
sun,  20.7"  C. 

Moist . . 

.022 
.017 

20.929 
20.931  i 

June  19 

37  25 

20  43W 

.... 

Moist . . 

.018;20.936' 
.01620.928 

.012  20.932 

June  20 

10  00  a.m. 

..    .. 

..    .. 

761.0 

Blowing 
from  sea 

Both    samples 
taken  a  t  Ponte 

Moist.. 

.019  20.931 1 
.013  20.929 1 

toward 

Delgada,  Azores, 

the  shore 

on  steamer, 

across  ship 

anchored  a  b  o  ut 
one  -  half   mile 
from  shore;  temp, 
on  deck.  20.5»  C. 

^1 

June  21 

12  15  p.m. 

40  04 

32  05W 

756.5 

Consider- 
able  SW. 

Night  before  clear; 
during  night,  sea 

Dry.... 
Dry. . . . 

.031 
.032 

20.930 1 

wind  dur- 

became  rough; 

Dry 

.031  20.931 

i  n  g  night 

6  a.  m.,  clouded 

Moist . . 

.01120.929 

beflre.^ 

over;  7  a.m.,  fog; 
11  a.m.,  quite 
clear. 

Moist . . 

.018  20.9381 

June  22 

41  07 

40  IIW 

.... 

Changed 
from  W.  to 

Clear  afternoon 
before;   windy; 

Dry. . . . 
Moist . . 

.030  20.932 
.013  20.932 

SW.;  high 

moist  in  morning. 

Moist  . . 

.018  20.927 

breeze. 

Moist . . 

.019  20.932 

June  23 

11  40  a.m. 

42  18 

47  42W 

753.0 

High  SW. 

Very   rough   sea 

Moist . . 

.018!  20.929 

11  45  a.m. 

eve  ning 

evening  before 

Moist . . 

.017 

■^yj.vAK} 

12  30  p.m. 

. .    . . 

. .    . . 

.... 

b  e  f  ore ; 
continued 
wind    in 
morning. 

and  during  night; 
early  morning, 
heavy  rain  (hail) ; 
clear  about  7  to  8. 

Dry.... 

.031 

20.937 

June  24 

42  49 

55  19W 

751.0 

Moist . . 

.027l2U.y3i  j 
.028120.931 1 

........... 

Moist . . 

.022  20.932 
.023  20.936 

DrV.'. . . 

.032  20.934 

June  25 

42  42 

63  33W 

759.0 

Moist . . 
Dry. . . . 

.014  20.936 
.033  20.929 

Average 

.... 

20.932 

108 


Composition  of  the  Atmosphere 


The  wisdom  of  taking  samples  dry  is  seen  from  these  results,  since  in 
all  dry  samples  the  percentage  of  carbon  dioxide  was  found  to  be  always 
normal.  The  oxygen  percentages  again  show  a  striking  uniformity  and 
constancy,  irrespective  of  geographical  location,  weather  conditions,  etc. 
ANALYSES  OF  AIR  FROM  PIKE'S  PEAK. 
The  interesting  expedition  to  the  top  of  Pike's  Peak  made  by  Haldane, 
Yandell  Henderson,  Douglas,  and  Schneider,  in  the  summer  of  1911,  was 
utilized  in  that  these  gentlemen  kindly  consented  to  collect  samples  of 
air  for  this  research.  The  apparent  constancy  in  composition  of  the 
cylinder  air  during  the  early  half  of  1911  led  to  the  belief  that  air  samples 
stored  in  steel  cylinders  would  not  undergo  a  material  loss  of  oxygen;  and 
obviously  samples  collected  in  this  way  would  give  opportunity  for  in- 
numerable analyses.  Consequently  three  small  steel  cylinders,  fitted 
with  proper  valves,  and  a  strong  bicycle  pump  were  sent  to  Professors 
Haldane  and  Henderson.  Both  these  gentlemen  questioned  seriously 
the  advisability  of  using  this  method  of  sampling,  and  fortunately  insisted 
upon  having  the  usual  glass  samplers  sent  to  them,  in  which  they  collected 
additional  samples.  The  analysis  of  the  air  from  Pike's  Peak  was  not  taken 
up  until  the  fall  of  1911.  At  this  time  it  was  found  that  during  the  sum- 
mer the  oxygen  percentage  of  the  air  in  the  control  cylinder  had  changed 
from  20.918  to  20.880,  this  not  inconsiderable  change  possibly  resulting 
from  the  extreme  heat  of  the  summer,  which  had  been  abnormal  for  this 
section.  Since  there  had  been  a  change  in  the  oxygen  content  of  this  air, 
it  was  seen  that  no  reliance  could  be  placed  upon  the  constancy  in  compo- 
sition of  air  stored  in  steel  cylinders,  so  that  any  results  which  might  be 
obtained  with  air  collected  in  this  way  on  Pike's  Peak  would  be  vitiated. 
Furthermore,  it  could  not  even  be  assumed  that  cylinders  filled  on  the 
same  day  and  under  the  same  conditions  would  be  equal  in  oxidation;  hence 
any  variations  from  the  normal  oxygen  content  found  at  sea-level  could  not 
reasonably  be  ascribed  to  a  persistent  regular  oxidation  in  the  cylinders. 
Table  66. — Analyses  at  Nutrition  Laboratory  of  air  from  summit  of  Pike's  Peak, 

[Air  collected  and  stored  in  steel  cylinders.] 


Data. 

Carbon 
dioxide. 

Oxygen. 

Data. 

Carbon 
dioxide. 

Oxygen. 

Collected  Aug.  6. 1911,  5  p.m.  J 
Wind,    moderate    N.W.  < 
Weather  clear.                       J 

p.ct. 

0.034 
.032 
.031 
.036 
.0.34 
.036 
.038 

p.  a. 

20.915 
20.918 
20.914 
20.923 
20.922 
20.928 
20.929 

Collected  Aug.  8, 1911,  5  p.m.  j 
Wind,   moderate   N.W.  \ 
Weather  clear.                      i 

p.ct. 

0.031 
.032 
.032 
.035 
.033 
.032 

p.ct. 

20.881 
20.883 
20.880 
20.886 
20.887 
20.889 

The  samples  of  air  collected  in  the  steel  cylinders  were  analyzed  be- 
tween September  20  and  October  5.  While  the  results  have  but  little 
value,  they  are  given  in  table  66  as  a  further  demonstration  of  the  inade- 
quacy of  this  method  of  preserving  air  samples.  The  very  large  differences 
in  the  oxygen  content  of  the  two  cylinders  bears  out  the  belief  that  the 


Comparative  Air-Analyses 


109 


oxidation  may  be  very  irregular.  The  percentage  of  carbon  dioxide  is 
slightly  higher  than  normal,  but  whether  this  is  due  to  oxidative  processes 
in  the  cylinder,  to  organic  matter  from  the  lubrication  and  rubber  hose  of 
the  bicycle  pump,  or  to  an  actual  condition  of  the  air,  the  results  do  not  show. 
The  samples  collected  in  glass  tubes  were  analyzed  October  9  and  10, 
1911,  the  results  in  table  67  being  obtained.  Although  some  samples 
stored  in  glass  have  a  strong  tendency  to  decrease  in  the  percentage  of 
carbon  dioxide,  these  analyses  show  a  percentage  which  is  approximately 
normal.  With  the  exception  of  the  results  obtained  for  August  14,  the 
oxygen  percentages  are  also  normal.  While  apparently  there  is  a  slight 
diminution  in  the  percentage  of  oxygen,  the  average,  20.927  per  cent,  is 
obviously  affected  by  the  results  for  August  14,  and  since  at  least  one 
analysis  on  each  of  the  three  days  showed  a  percentage  of  20.930  or  over, 
it  seems  hardly  probable  that  this  apparent  slight  decrease  is  significant. 

Table  67. — Analyses  made  at  the  Nutrition  Laboratory  of  air  collected  on  summit  of 

Pike's  Peak— 4312  meters. 

[Air  collected  and  stored  in  glass  samplers.] 


Date  of 
collection. 


1911. 
Aug.  11 

Aug.  11 

Aug.  12 


Aug.  14 
Aug.  14 


Time. 


6h00n>p.m. 
6  00  p.m. 
9  00  p.m. 
9  00  p.m. 
10  00  a.m. 


8  30  a.m. 
8  30  a.m. 

5  30  p.m. 
5  30  p.m. 


Barom- 
eter. 


mm. 
459 
459 
459 
459 
458 


462 
462 

462 
462 


Wind. 


Weather. 


Strong 
...Do 
...Do 
...Do 
...Do 


Gentle 
...Do 

Very 

NE. 


W... 


N.., 
Ught 


Average 


f  1  hr.  after  snowstorm  with 
I   much  lightning. 

I  Somewhat  clearer;  32°  F 

Partly   sunshine,    partly 
driving  clouds;    beginning 
to  clear  and  wind  fall- 
ing, 
r Beautiful   clear   day;     day 
-<    and  night  before  clear  and 
t  warm. 


Carbon 
dioxide. 


p.  ct. 

0.027 

.032 


.029 


.031 
.029 

.031 


Oxygen. 


p.  ct. 
20.928 
20.936 
20.932 
20.930 
20.930 


20.911 
20.923 

20.932 
20.921 
20.927 


ANALYSES  OF  STREET  AIR. 

While  the  air  in  the  vicinity  of  the  laboratory  would  be  expected 
to  be  somewhat  contaminated  with  carbon  dioxide  and  consequently 
deficient  in  oxygen,  it  is  obvious  that  the  contaminating  factors  are  not 
of  sufficient  magnitude  to  affect  perceptibly  the  analytical  results.^  It 
became  a  question  of  interest,  however,  as  to  how  far  one  must  go  into 
the  heart  of  the  city  to  secure  air  of  less  than  normal  oxygen  content. 
Two  samples  were  therefore  collected,  in  containers  fitted  with  excellent 
glass  stop-cocks,  from  a  crowded  business  street.  The  results  of  the 
analyses  are  given  in  table  68. 

The  percentage  of  oxygen  was  slightly,  though  almost  imperceptibly, 
less  than  that  in  normal  air,  while  the  carbon  dioxide  was  slightly  higher 
than  the  average  normal.  Since  by  reference  to  table  61  it  can  be  seen 
that  the  samples  analyzed  at  the  laboratory  on  the  same  date  showed 
20.939  per  cent  of  oxygen  and  0.029  per  cent  of  carbon  dioxide,  it  can  be 


110 


Composition  of  the  Atmosphere 


safely  asserted  that  this  apparatus  was  sufficiently  sensitive  to  show  even 
the  slight  contamination  produced  by  the  congestion  of  population  in  a 
narrow  city  street.  It  is  also  remarkable  that  under  these  conditions 
the  carbon-dioxide  increment  and  oxygen  deficiency  were  not  very  much 
greater.  Observations  such  as  these  tend  to  demonstrate  the  extent  of 
the  diffusion  of  gases  and  the  establishment  of  equilibrium  by  air-currents. 

Table  68. — Analyses  made  at  the  Nutrition  Laboratory  of  air  collected  on  a  crowded 
business  street  in  Boston. 


Date. 

Time. 

Baxometer. 

Temper- 
ature. 

Place. 

Carbon 
dioxide. 

Oxygen. 

1911. 
Nov.  14 

Nov.  14 

p.m. 

1^30- 

140 

mm. 

769.55 
769.55 

°C. 

2.7 
2.7 

In  Washington  st.  between 
Summer  and  Avon  sts 

In  Washington  st.  between 
Summer  and  Franklin  sts . 

p.ct. 

0.031 
.032 
.032 
.034 

p.ct. 

20.930 
20.929 
20.929 
20.929 

ANALYSES  OF  SUBWAY  AIR. 
Although  foreign  to  the  major  question  here  studied,  namely,  the 
composition  of  uncontaminated  air,  it  was  also  of  interest  to  find  out  to 
what  extent  the  air  was  vitiated  in  the  modern  "tube"  or  "subway"  so 
extensively  used  for  suburban  passenger  traffic.  Two  samples  taken  si- 
multaneously at  the  Park  Street  station  in  the  Boston  subway  gave  the 
results  presented  in  table  69. 

Table  69. — Analyses  made  at  the  Nutrition  Laboratory  of  air  collected 
at  the  Park  Street  station  of  the  Boston  subway. 


Date. 

Sample. 

Time. 

Carbon 
dioxide. 

Oxygen. 

1911. 
Oct.  25 

Oct.  25 

I 
II 

9»»30'«a.m. 
9  30  a.m. 

p.  ct. 

0.064 
.062 
.065 

20;^3 
20.898 
20.897 

The  samples  were  taken  immediatedly  after  the  "rush  hours"  were 
ended  and  when  the  oxygen  content  of  the  air  in  the  subway  might  be  ex- 
pected to  be  at  a  minimum.  The  fall  of  approximately  0.03  per  cent  in 
oxygen  is  accompanied  by  a  rise  of  0.032  per  cent  in  the  carbon  dioxide. 
Here  again  one  is  divided  between  appreciation  of  the  extraordinary  sen- 
sitiveness of  the  Sond^n  apparatus  and  surprise  that  the  circulation  of 
air  in  the  subways  can  be  so  good  and  the  diffusive  power  of  air  so  ex- 
tended that  the  increases  in  carbon  dioxide  and  decreases  in  oxygen  are  of 
such  slight  amount. 

Thanks  to  the  kindness  of  Dr.  E.  F.  DuBois  and  Dr.  Warren  T.  Cole- 
man, two  specimens  of  air  were  collected  from  the  subway  in  New  York 
City.  The  results,  which  are  given  in  table  70,  differ  in  no  wise  from 
those  found  in  the  Boston  subway  and  show  an  increase  in  carbon  dioxide 
and  decrease  in  oxygen  infinitely  less  than  one  would  normally  have  ex- 
pected. 


Comparative  Air-Analyses 


111 


Table  70.— 

•Analyses  made  at  the  NutrUion  Laboratory  of  air  collected  in  the  subway, 
in  New  York  City, 

Date. 

Time. 

Place. 

Carbon 
dioxide. 

Oxygen. 

1911. 

Nov.  21 
Nov.  21 

e^'OS'^p.m. 
(rush  hour) 
5  52  p.m. 

Grand  Central  subway  station  .... 
Between  110th  and  96th  sts 

p.et. 
0.061 

.071 

Am 

20.897 

The  results  of  this  series  of  experiments  have  a  particular  value,  inas- 
much as  they  show  clearly  that  a  decrease  in  oxygen  is  accompanied  by  an 
approximate  increase  in  carbon  dioxide.  While  the  measurement  of  car- 
bon dioxide  has  been  taken  as  an  index  of  good  or  bad  ventilation,  the  fact 
that  the  proportion  of  oxygen  is  actually  lowered  by  an  increase  in  the 
carbon  dioxide  has  never  before  been  clearly  demonstrated.  As  a  result 
of  this  study,  however,  knowing  both  the  constancy  of  oxygen  in  outdoor 
air  and  the  sources  of  carbon-dioxide  production,  and  knowing  also  that 
with  the  carbon-dioxide  production  there  must  likewise  be  an  oxygen 
consumption,  we  can  safely  state  that  for  every  one-hundredth  per  cent 
of  increase  in  carbon  dioxide  there  will  be  approximately  one-hundredth 
per  cent  decrease  in  oxygen.^  It  will  be  seen,  therefore,  that  since  there 
are  a  number  of  simple  and  accurate  methods  for  determining  carbon 
dioxide,  the  time-consuming  and  complicated  determinations  of  oxygen 
are  entirely  unnecessary,  as  the  determination  of  the  percentage  of  car- 
bon dioxide  in  the  air  estabUshes  the  approximate  percentage  of  oxygen. 

ABSORPTION  OF  OXYGEN  BY  POTASSIUM  PYROGALLATE. 

Since  the  constancy  of  the  oxygen  content  of  the  air  has  been  demon- 
strated in  this  research,  it  has  been  possible  to  make  a  more  accurate 
study  than  heretofore  of  the  conditions  affecting  the  absorption  of  oxygen 
by  potassium  pyrogallate.  Many  investigators  have  experimented  with 
potassium  pyrogallate  as  an  absorbing  agent  for  oxygen;  but  inasmuch  as 
there  appeared  to  be  fluctuations  in  the  oxygen  content  of  the  air,  they 
have  sought  for  the  maximum  absorption  capacity  and  minimum  produc- 
tion of  carbon  monoxide  without  attempting  to  control  the  absorption 
of  oxygen.  Particularly  confusing  has  been  the  fact  that  the  potassium 
hydroxide  as  found  on  the  market  varies  greatly  in  its  water  content, 
the  amount  ranging  from  5  to  25  per  cent. 

To  investigators  on  this  subject,  the  experience  of  Haldane  and  Hem- 
pel  has  been  of  the  most  interest.  As  abeady  stated,  the  use  in  this 
research  of  Haldane's  saturated  solution  of  potassium  hydroxide  for  dis- 
solving the  pyrogallol  did  not  seem  wise  with  so  delicate  an  apparatus  as 
ours.  Should  there  be  a  complete  solidification  of  the  reagent  in  chamber 
D,  considerable  time  would  be  required  to  get  the  solution  again  in  con- 

1  The  one  inexplicable  phenomenon  is  the  abnormaUy  high  percentage  of  carbon 
dioxide  found  in  the  air  of  Greenland  by  Krogh. 


112  Composition  op  the  Atmosphere 

dition  for  use;  this  would  result  in  delay,  with  always  a  possibility  that 
the  expansion  might  fracture  the  glass  vessel.  Furthermore,  as  the  slightly 
more  dilute  solution  ultimately  used  for  the  routine  analyses  was  so  much 
stronger  than  the  solution  recommended  by  Hempel,  it  was  thought  that 
the  coefficient  of  absorption  rather  than  the  completeness  of  absorption 
would  be  sacrificed  by  employing  a  less  concentrated  solution.  *  In  the 
supplementary  study  made  of  the  comparative  value  of  the  various  potas- 
sium pyrogallate  solutions,  the  formulas  recommended  by  both  Haldane 
and  Hempel  were  tested  as  to  their  absorptive  powers.  In  all,  four  dif- 
ferent solutions  were  used: 

(1)  Hempel's  solution,  prepared  according  to  his  formula.  Five  grams 
of  pyrogallol  were  dissolved  in  15  c.  c.  of  water  and  mixed  with  120 
grams  of  potassium  hydroxide  dissolved  in  80  c.  c.  of  water.  Stick  potas- 
sium hydroxide  not  purified  by  alcohol  was  used  in  all  the  solutions. 

(2)  Hempers  solution,  prepared  by  a  modified  formula.  Inasmuch  as 
stick  potassium  hydroxide  contains  from  5  to  25  per  cent  of  water,  instead 
of  using  120  grams  of  stick  potassium  hydroxide  as  in  the  first  solution, 
only  sufficient  was  used  to  be  equivalent  to  120  grams  of  anhydrous 
potassium  hydroxide.  To  maintain  the  proper  proportion  of  water,  the 
amount  in  the  stick  caustic  potash  was  included  in  the  80  grams  required 
by  Hempel's  formula.  As  the  particular  lot  of  stick  caustic  potash  in  use 
at  that  time  was  found  by  alkalimetry  to  contain  92  per  cent  of  potassium 
hydroxide,  130  grams  of  this  chemical  was  mixed  with  70  c.  c.  of  water  and 
subsequently  the  5  grams  of  pyrogallic  acid  added. 

(3)  The  potassium  pyrogallate  solution  used  throughout  this  research. 
This  is  described  on  p.  80. 

(4)  Haldane's  formula,  requiring  a  saturated  solution  of  potassium 
hydroxide  in  water,  with  a  specific  gravity  of  1.55.  The  solution  is  made 
in  the  proportion  of  1  gram  of  pyrogallic  acid  to  10  c.  c.  of  the  potassium- 
hydroxide  solution  and  hence  has  the  greatest  density  of  all  the  solutions. 

For  purposes  of  comparison,  both  outdoor  air  and  cylinder  air  were 
analyzed  in  this  study,  exactly  the  same  routine  being  followed  in  all 
analyses,  and  with  all  four  solutions.  (See  p.  100.)  The  results  are  in- 
corporated in  table  71. 

The  results  of  these  two  series  of  analyses  point  conclusively  to 
marked  differences  in  the  results  obtained  with  solutions  of  varying 
strength.  These  differences  may  be  attributed  either  to  an  incomplete- 
ness of  absorption  or  to  the  formation  of  carbon  monoxide.  That  in- 
completeness of  absorption  by  the  weaker  solutions  can  account  in  any 
measure  for  the  differences  here  observed  seems  hardly  probable  when  the 
analyses  for  January  26,  1912,  are  considered.  The  results  obtained 
on  that  date  show  that  extending  the  time  during  which  the  air  was  in 
contact  with  the  reagent  for  an  additional  12  minutes  made  barely  an 

1  For  a  criticism  of  the  use  of  potassium  pyrogallate  as  an  absorbent  of  oxygen,  see 
B,  lacke,  Archiv  fur  die  gesammte  Physiologic,  1886,  38,  p.  401. 


Comparative  Air-Analyses 


113 


appreciable  increase  in  the  percentage  of  oxygen.  Furthermore,  for  fear 
that  simple  contact  might  be  inefficient,  as  a  further  precaution,  in  cer- 
tain analyses  on  January  31  and  February  1,  the  gas  was  passed  into  the 
potassium  pyrogallate  10  times  at  the  end  of  the  regular  routine,  but 
with  no  appreciable  increase  in  oxygen  percentage. 


Table  71. — ResvUs  of  comparative  study  of  oxygen  absorption 
solutions  of  varying  concentraiion. 


potassium  pyrogallate 


Date. 

Outdoor  air. 

Cylinder  air. 

Hempel 

Bolution. 

I. 

^  Hempel 

'solution. 

II. 

Regular 
solution. 

Haldane 
solution. 

Hempel 

solution. 

I. 

Hempel 

solution. 

II. 

Regular 
solution. 

Haldane 
solution. 

1912. 

p.ct. 

p.ct. 

p.ct. 

p.ct. 

p.  ct. 

p.ct. 

p.ct. 

p.  ct. 

Jan.    6 

20.933 
20.939 
20.940 

.... 

20.860 
20.860 

Jan.    9 

.... 

.... 

20.940 
20.941 
20.933 

.... 

.... 

.... 

20.872 
20.862 
20.863 

Jan.  26 

20.848 
20.849 
20.843 
120.857 
120.852 
120.854 
120.852 

20.759 
120.773 

Jan.  27 

20.952 
20.958 
20.950 
20.950 
20.952 

20.879 
20.878 
20.875 

Jan.  30 

20.910 
20.917 
20.918 
20.910 
20.911 

20.828 
20.830 
20.832 

Jan.  31 

20.949 
20.958 
220.953 
220.960 
220.975 

Feb.    1 

.... 





III 

.... 

.... 

.... 

.... 

Average 

220.954 

20.851 

20.913 

20.938 

20.956 

20.766 

20.830 

20.863 

20^77 

1  These  were  given  an  additional  12  minutes  in  the  potassium-pyrogallate  solution. 

2  After  absorbing  the  oxygen  in  the  regular  way,  the  air  was  sent  back  and  forth  into  the  potassium- 
pyrogallate  solution  10  times  before  the  reading  was  taken. 

Since  the  obvious  inference  is  that  there  must  have  been  a  slight  for- 
mation of  carbon  monoxide  with  the  weaker  solutions,  one  questions 
immediately  if  it  is  certain  that  even  with  the  strong  Haldane  solution 
there  may  not  be  traces  of  carbon  monoxide.  Haldane's  experience  in 
detecting  minute  amounts  of  carbon  monoxide  goes  a  long  way,  however, 
in  establishing  faith  in  his  assertion  that  not  the  slightest  trace  is  found 
with  the  use  of  his  concentrated  solution. 


114 


Composition  of  the  Atmosphere 


CONCLUSIONS. 

(1)  Apparatus  for  gas-analysis. — The  Sonden  apparatus  here  de- 
scribed fulfills  all  conditions  essential  to  exact  gas-analysis,  save  that  the 
gas  is  not  measured  dry  in  a  dry  pipette  over  mercury.  In  spite  of  this 
one  drawback,  the  technique  has  been  developed  so  as  to  insure  a  con- 
stancy and  sensitiveness  found  as  yet  in  no  other  form  of  gas-analysis 
apparatus. 

(2)  Reagent  for  the  absorption  of  oxygen. — Experimentation  with  all 
forms  of  absorbents  for  oxygen,  including  several  strengths  of  potassium 
pyrogallate  solution,  leads  inevitably  to  the  conclusion  that  the  Haldane 
potassium-pyrogallate  solution  is  the  most  efficient  agent  thus  far  recom- 
mended. The  analyses  of  those  investigators  employing  phosphorus  or 
sodium  hydrosulphite  do  not  lead  one  to  believe  that  for  eflSciency  they 
can  supersede  the  Haldane  solution. 

(3)  The  constancy  of  the  oxygen  percentage  in  outdoor  air. — The  results 
of  analyses  of  air  taken  near  the  laboratory  showed  no  material  fluctua- 
tion in  oxygen  percentage  during  a  period  extending  from  April  15,  1911, 
to  January  30,  1912.  This  constancy  was  maintained  in  spite  of  all 
possible  alteration  in  weather  conditions,  changes  in  barometer,  ther- 
mometer, humidity,  and  wind  direction  and  strength;  furthermore,  the 
experiments  were  made  before,  during,  and  after  the  vegetative  season. 
The  average  result  of  212  analyses  showed  0.031  per  cent  of  carbon  dioxide 
and  20.938  per  cent  of  oxygen.  The  analyses  of  air  collected  over  the 
ocean,  at  two  different  times  of  the  year,  and  on  the  top  of  Pike's  Peak, 
gave  essentially  similar  results.  The  average  results  of  all  the  analyses 
made  in  this  research  of  outdoor  air  are  summarized  in  table  72. 

Table  72. — Summary  of  analyses  made  at  ike  Nutrition  Laboratory  of  outdoor  air. 


Number  of 
analyses. 

Carbon 
dioxide. 

Oxygen. 

Oxygeni 
(corrected). 

Air  near  laboratory 

212 

7 

36 

9 

p.ct. 

0.031 

p.  ct. 

20.938 
20.936 
20.932 
20.927 

p.  et. 
20.952 
20.950 
20.946 
20.941 

Ocean  air  (Montreal-Liverpool) .  . . 

Ocean  air  (Genoa-Boston) 

Pike's  Peak 

1  A  correction  of  0.014  has  been  added  to  the  average  results  obtained  in  this  research  to  make  them 
comparable  with  results  secured  with  the  Haldane  solution.    (See  p.  113.) 

(4)  The  absolute  oxygen  content  of  outdoor  air. — While  this  research 
has  dealt  mainly  with  comparative  values,  certain  fundamental  difficul- 
ties in  method  and  technique  prevent  deductions  with  regard  to  the  ab- 
solute oxygen  content  of  outdoor  air.  The  use  of  the  Haldane  concen- 
trated potassium-pyrogallate  solution  would  seem  to  preclude  the  pos- 
sibility of  the  formation  of  measurable  amounts  of  carbon  monoxide,  but 
we  always  have  to  deal  with  the  possible  error  in  the  water  adhering 
to  the  pipette  when  the  change  in  level  of  the  mercury  is  made.  Since 
the  contraction  in  volume  is  assumed  to  be  only  that  due  to  absorbed 
oxygen,  and  since  unquestionably  some  water  is  confined  between  the 


Comparative  Air- Analyses  115 

glass  and  the  mercury,  the  contraction  as  measured  is  invariably  too 
large  by  the  volume  of  the  water  so  held.  Unfortunately  no  quantita- 
tive measurements  of  this  water  are  possible  with  the  Sond^n  apparatus. 
In  this  study,  however,  we  have  aimed  to  secure  constancy  in  the  amount 
of  water  thus  trapped,  knowing  that  the  absolute  amount  could  not  be 
measured.  The  analyses  of  both  outdoor  and  cylinder  air  with  the  potas- 
sium pyrogallate  employed  in  this  research,  as  well  as  the  analyses  made 
with  Haldane's  strong  solution,  showed  invariably  that  the  correction  of 
+  0.014  should  be  added  to  the  results  given  to  make  them  comparable 
with  analyses  made  with  the  Haldane  solution. 

The  atomic  weights  of  but  few  of  the  chemical  elements  are  known  to  1 
part  in  2000,  and  hence  it  may  now  rightly  be  said  that  air  is  a  physical 
mixture  with  the  definiteness  of  composition  of  a  chemical  compound. 

(5)  While  the  combustion  of  fuel  and  the  vital  processes  of  men  and 
animals  result  in  a  local  increase  in  carbon  dioxide  and  decrease  in  oxy- 
gen on  the  one  hand,  and  vegetable  growth  results  in  a  decrease  in  carbon 
dioxide  and  increase  in  oxygen  on  the  other,  the  extraordinary  rapidity 
wilh  which  the  local  variations  in  the  composition  of  the  air  are  equalized 
is  accentuated  by  the  observations  on  street  air,  which  show  but  the 
slightest  trace  of  an  oxygen  deficit. 

The  ratio  between  the  increment  in  carbon  dioxide  and  the  decrease 
in  oxygen  leads  naturally  to  the  conclusion  that  carbon-dioxide  deter- 
minations may  be  taken  as  excellent  indications  of  the  oxygen  content 
and  thus  the  necessity  for  elaborate  and  time-consuming  oxygen  determin- 
ations disappears.  For  every  0.01  per  cent  increase  in  the  atmospheric 
carbon  dioxide,  one  may  safely  assume  a  corresponding  decrease  in  the 
percentage  of  oxygen. 

Nutrition     Laboratory    of    the    Carnegie    Institution    op    Washington, 

Boston,  Massachusetts,  February  19, 1912. 


UNIVERSITY    OF    CALIFORNIA 
BRANCH    OF    THE   COLLEGE    OF   AGRICULTURE 

THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BEI<OW 


my  2 1 1930 

6  JAN  '69 

JAN  ^   REC'D 

lUCD  UBRARY 

|dUE0CT22^9;^ 

OCT  8  mi 


LIBRARY,  BRANCH  OF  THE  COUtGE  OF  AGRICULTURE 


